2.0.1 (2026-09-01)

Fixed

• Added QuicConnection.should_wait_for_ack(now) as the supported replacement
  for inspecting private loss-recovery state when coordinating flow control manually.
• Missing typing on some key methods in QuicConnection such as get_peercert.

2.0.0 (2026-08-31)

Changed

• Rebuilt QuicConnection around a single authoritative Rust transport core.
  The pure-Python packet-processing path had reached a practical performance
  ceiling that incremental optimization could no longer overcome. Rather than
  replacing the implementation with an unrelated QUIC stack, we ported and
  preserved the years of protocol, interoperability and recovery work inherited
  from aioquic and subsequently developed in qh3. The public Python
  facade remains familiar, and Python continues to own TLS policy, certificates,
  ALPN, ECH and session tickets, while Rust now owns packet protection, frame
  processing, streams, flow control, connection IDs, paths, congestion control
  and loss recovery. This is an intentional major-version change: private
  QuicConnection internals are no longer compatible with the former
  pure-Python implementation.
• Updated aws-lc-rs v1.17.1 to v1.18.0
• Updated rustls v0.23.41 to v0.23.43

1.9.4 (2026-07-12)

Fixed

• Congestion and loss algorithms against more brittle network connections

Changed

• Updated lsqpack to v2.6.5 via our ls-qpack-rs crate v0.3.2

1.9.3 (2026-07-08)

Changed

• Updated aws-lc-rs v1.17.0 to v1.17.1
• Updated rustls v0.23.40 to v0.23.41
• Downgraded every DEBUG log entry to a TRACE (5) level to avoid spamming people who set level at interpreter scale for logging

1.9.2 (2026-06-05)

Fixed

• Added guard against too large msg (during PING frame probe) datagram in non-GSO/quinn-udp path.

1.9.1 (2026-06-01)

Fixed

• Handshake failure (got type 20, wanted type 8) against servers that accept the
  TLS application_settings (ALPS) offer.

1.9.0 (2026-05-31)

Changed

• Total refresh of default QUIC and HTTP3 parameters to better blend in with mainstream browser traffic.
  • Key shares are now only sent for X25519MLKEM768 and X25519. The NIST P-curves (secp256r1, secp384r1)
    remain advertised but a share is only generated on demand.
  • Ed25519 is no longer advertised in signature_algorithms by default.
  • supported_versions now defaults to QUIC v1 only. v2 become opt-in.
  • The TLS status_request (OCSP) extension is no longer offered.
  • active_connection_id_limit is no longer advertised by default.
• Updated aws-lc-rs v1.16.3 to v1.17.0

Added

• Certificate compression (RFC 8879) on receive using Brotli, enabled when the brotli (CPython) or brotlicffi (PyPy) package is installed.
• Escape hatches in QuicConfiguration to opt back into the former behaviors: signature_algorithms,
  offer_ec_key_shares, offer_certificate_status_request and active_connection_id_limit.

Fixed

• Disabled Apple private batch recv/send calls by default until further investigate.
  Private reports found that in some specialized networking environment it would induce
  unstable and often lost datagrams.
• Swapped bare assert statement in favor of unavoidable hard checks and raises.
• H3 trailers event handler did not check for trailing data.
• A trailing FIN on a stream already torn down by reset / stop-sending could resurrect it,
  delivering a spurious duplicate stream and leaking its asyncio StreamWriter.

1.8.1 (2026-05-07)

Fixed

• Remediation on various QUIC compliance items (enabled by 3rd party audit).
  • fix(recovery): compliance batch
  • fix(crypto): retain previous recv keys for 3 PTO
  • fix(connection): stateless reset, CONNECTION_CLOSE retransmit, idle-timer floor
  • fix(stream): FINAL_SIZE_ERROR, send-only stream cleanup
  • fix(h3): surface StreamReset / StopSending events; enforce critical stream closure
  • fix(packet): reject duplicate transport parameters
  • fix(recovery): implement missing HyStart++
  • fix(recovery): MTU probe through ping frame mistaken as real loss
  • chore: raise initial_rtt default to 333 ms

1.8.0 (2026-05-03)

Changed

• Aggressive optimizations in the library. Expect up to 30% improvement in general. We are aware that qh3 have a significant part of the logic in pure Python and we are trying to migrate some of that logic into Rust but it takes a significant time to arrive. We prefer small incremental changes that we can be confident about.
• Updated rustls to 0.23.40
• Per space packet number instead of a single one for QUIC compliance.

Fixed

• Erroneous PTO loss detector under high pressure.
• Duplicate datagram eviction.
• Effective keepalive did not respect remote max keepalive.

Added

• Goaway event for the HTTP/3 state machine.
• GRO/GSO support when available. Native support for Linux and via MacOS private batching API otherwise fallback to native datagrams reader/writer. Windows support for URO (equivalent of GRO) is scheduled in a future release. We are currently investigate how stable it is due to recent report of unstability in Firefox.

1.7.4 (2026-04-28)

Fixed

• Unexpected crash when a corrupted datagram is fed into the QUIC state machine.

Changed

• Updated rustls v0.23.38 to v0.23.39

1.7.3 (2026-04-22)

Fixed

• Performance issue on first TLS handshake due to an unnecessary CA store self signature check.

1.7.2 (2026-04-20)

Fixed

• HTTP/3 SETTINGS_H3_DATAGRAM identifier now uses the RFC 9297 value 0x33 instead of the obsolete draft ietf masque value 0xFFD277. This fixes interop with RFC 9297-compliant peers. The legacy identifier is still accepted on receive for backward compatibility. (https://github.com/jawah/qh3/issues/107)

Changed

• Updated aws-lc-rs v1.16.2 to v1.16.3
• Updated pyo3 v0.28.2 to v0.28.3
• Updated rustls v0.23.37 to v0.23.3

1.7.1 (2026-03-30)

Fixed

• ls-qpack-rs strict enforcement struct assert at build time. (https://github.com/jawah/qh3/issues/105)

Changed

• Updated aws-lc-sys v0.39.0 to v0.39.1.
• Updated ls-qpack-rs v0.3.0 to v0.3.1.

Misc

• Missing ARM64 pre-built wheel for Windows non freethreaded build. (https://github.com/jawah/qh3/issues/106)

1.7.0 (2026-03-23)

Added

• Encrypted Hello (ECH) support based on RFC 9849 specifications. We do not support ECH for the server-side. Only intended for client-side usage.

Changed

• Updated aws-lc-rs v1.16.0 to v1.16.2 (aws-lc-sys/aws-lc relicensed to Apache-2.0)
• Updated lsqpack implementation v2.6.1 (e33719e) to v2.6.2 (1e9c5b8) via ls-qpack-rs v0.3.0.

Fixed

• True GREASE following RFC 8701.

Security

• Fixed AWS-LC X.509 Name Constraints Bypass via Wildcard/Unicode CN (GHSA-394x-vwmw-crm3)
• Fixed CRL Distribution Point Scope Check Logic Error in AWS-LC (GHSA-9f94-5g5w-gf6r)

Misc

• Release the GIL during qpack encode and decode operations.

1.6.0 (2026-03-01)

Added

• Client side MTU discovery to probe for max datagram size.
• Setting UDP datagram size at configuration level. (#69)
• SBOM artifact (cyclonedx) for the Rust side is now generated and integrated into the pre-built wheel.

Changed

• Updated aws-lc-rs v1.14.0 to v1.16.0
• Minor performance improvement in hot code paths.
• Remove default Reno congestion algorithm in favor to the Cubic implementation (RFC 9438).

1.5.6 (2025-11-09)

Fixed

• backport (https://github.com/aiortc/aioquic/pull/604) avoid assertion error when receiving multiple STOP_SENDING.
• backport (https://github.com/aiortc/aioquic/pull/603) limit the number of remote path challenges stored per path.
• backport (https://github.com/aiortc/aioquic/pull/606) update PATH_CHALLENGE / PATH_RESPONSE state after sending.
• backport (https://github.com/aiortc/aioquic/pull/606) send PATH_CHALLENGE before other frame types.
• backport (https://github.com/aiortc/aioquic/pull/590) remove stream objects when stream is ended.

Changed

• Various minor performance improvements in our Rust code.

Misc

• OCSP internals improved for better reliability (niquests usage only).

1.5.5 (2025-10-05)

Changed

• Upgraded aws-lc-rs to v1.14.0
• Upgraded rustls to v0.23.32
• Upgraded pyo3 to v0.26.0

Added

• Explicit support for Python 3.14

Misc

• Initial support for pre-built RISCV wheels

1.5.4 (2025-08-11)

Changed

• Upgraded aws-lc-rs to v1.13.3
• Upgraded rustls to v0.23.31

Misc

• OCSP and CRL related helpers improved. This is not useful for end users of qh3.

1.5.3 (2025-06-16)

Removed

• The caextra recently added in the Configuration is reverted. After much consideration this was a mistake. End-users are already pushing either willingly or by accident intermediate CA or even non TLS client auth or server auth certificate in the regular CA bundle. We had to find another way.

Changed

• Caching the trust store loading in-memory to avoid unnecessary overhead on each TLS handshake.
• Upgraded pyo3 to 0.25.1

Fixed

• Aligned our TLS certificate chain validation with CPython+OpenSSL default behaviors. Pushing intermediates CA in the main CA bundle will still require that the trust anchors (root ca) is present.

Misc

• Changed CRL helpers and add the validation layer (signature).
• Added the validation layer to OCSP response (signature).

1.5.2 (2025-06-01)

Added

• Passing extra intermediates CA in the configuration so that we could discretely rebuild the chain before validation. This is most useful in a corporate environment where server may misbehave and miss sending the full chain in the TLS handshake. The list of intermediate may be available in the OS trust store. It is not fetched automatically, you will have to provide them in the configuration. See the caextra property.

Fixed

• Default CA root list loading when none are given.

Changed

• Upgraded aws-lc-rs to 1.13.1
• Upgraded rustls to 0.23.27
• Upgraded pyo3 to 0.25.0

Misc

• Added CRL helpers.

1.5.1 (2025-05-02)

Fixed

• Parsing of SEC1/PKCS8 EC Private Key. https://github.com/jawah/qh3/issues/73

1.5.0 (2025-04-20)

Misc

• General performance improvements in various parts of the code. Up to 5% faster (against 1.4.5).

Changed

• GIL is now released during AEAD encryption/decryption.

Added

• OCSP stapling support for the client.

1.4.5 (2025-04-17)

Misc

• General performance improvements in various parts of the code. Up to 15% faster (against 1.4.4).

Fixed

• unclosed StreamWriter warning in our asyncio Protocol implementation.

Removed

• submodule qh3.buffer as well as qh3._crypto. Those were not supposed to be used externally anyway.

1.4.4 (2025-04-11)

Misc

• General performance improvements in various parts of the code. Up to 25% faster.

1.4.3 (2025-04-07)

Changed

• ls-qpack updated to v2.6.1 with a fix for big endian architectures (e.g. s390x).
• no longer using git fork to build qh3 with ls-qpack
• Upgraded aws-lc-rs to 1.13.0
• Upgraded pyo3 to 0.24.1

1.4.2 (2025-03-06)

Changed

• Upgraded aws-lc-rs from 1.12.2 to 1.12.5
• Upgraded pyo3 from 0.23.4 to 0.23.5

Misc

• Support for PyPy 3.11

Fixed

• Asyncio Protocol may raise AssertionError upon closing if the FIN bit was already sent in a given stream.

1.4.1 (2025-02-05)

Fixed

• Bad IDNA label raise inappropriate exception.

1.4.0 (2025-02-05)

Added

• Support for IDNA domain name using UTS 46 for both server and client

Changed

• Upgraded aws-lc-rs to 1.12.2

1.3.2 (2025-01-20)

Changed

• Upgraded aws-lc-rs to 1.12.1

Misc

• x86 (32-bits) wheels are now automatically published to PyPI for both Linux (i686) and Windows (win32). (#45)

1.3.1 (2025-01-15)

Changed

• Updated pyo3 from 0.23.3 to 0.23.4

1.3.0 (2025-01-01)

Changed

• Post-Quantum key-exchange Kyber 768 Draft upgraded to standard Module-Lattice 768.
• Version negotiation no longer logged as INFO. Every logs generated will always be DEBUG level.
• Converted our test suite to run on Pytest instead of unittest.
• Migrated pyo3 from 0.20.3 to 0.23.3

Fixed

• Clippy warnings in our Rust code.
• Rust code may panic due to lack of proper result unpacking on the cryptographic calls. Now any error will raise exception CryptoError instead.
• Negotiating post-quantum key exchange (server side).

Added

• noxfile.
• miscellaneous serialize/deserialize for Certificate, and OCSPResponse.
• Initial support for Python 3.13 freethreaded experimental build.

1.2.1 (2024-10-15)

Fixed

• Large HTTP headers cannot be encoded to be sent.

Changed

• Upgrade aws-lc-rs to v1.10.0
• Update rustls to v0.23.14

1.2.0 (2024-09-28)

Added

• Support for informational response 1XX in HTTP/3. The event InformationalHeadersReceived has been added to reflect that.

Changed

• Update rustls v0.23.12 to v0.23.13 along with dependents.

1.1.0 (2024-09-20)

Added

• Support for Post-Quantum KX Kyber768 (NIST Round 3) with X25519.
• Backport "QUIC Version 2". "Rework packet encoding to support different protocol versions" https://github.com/aiortc/aioquic/commit/bd3497cce9aa906c47d5b7216752f55beed3d9d3 "Add encryption for QUIC v2" https://github.com/aiortc/aioquic/commit/abf51897bb67f459921e4c26c8b3ea445aa79832 "Refactor retry / version negotiation handling" https://github.com/aiortc/aioquic/commit/70dd040893d7d8af5a2a92361c1e844ebf867abb "Add support for version_information transport parameter" https://github.com/aiortc/aioquic/commit/a59d9ad0b1df423376bf8b30ebb7642861fef54e "Check Chosen Version matches the version in use by the connection" https://github.com/aiortc/aioquic/commit/a59d9ad0b1df423376bf8b30ebb7642861fef54e

Changed

• Insert GREASE in KX, TLS Version and Ciphers.
• Backport "Only buffer up to 512 KiB of pending CRYPTO frames" https://github.com/aiortc/aioquic/commit/174a2ebbe928686ef9663acc663b3ac06c2d56f2
• Backport "Improved path challenge handling" https://github.com/aiortc/aioquic/commit/b507364ea51f3e654decd143cc99f7001b5b7923
• Backport "Limit the number of pending connection IDs marked for retirement." https://github.com/aiortc/aioquic/commit/4f73f18a23c22f48ef43cb3629b0686757f096af
• Backport "During address validation, count the entire received datagram" https://github.com/aiortc/aioquic/commit/afe5525822f71e277e534b08f198ec8724a7ad59
• Update aws-lc-rs v1.8.1 to v1.9.0
• Default supported signature algorithms to: ECDSA_SECP256R1_SHA256, RSA_PSS_RSAE_SHA256, RSA_PKCS1_SHA256, ECDSA_SECP384R1_SHA384, RSA_PSS_RSAE_SHA384, RSA_PKCS1_SHA384, RSA_PSS_RSAE_SHA512, RSA_PKCS1_SHA512, ED25519.

Fixed

• Certificate fingerprint matching.
• Backport upstream urllib3/urllib3#3434: util/ssl: make code (certificate fingerprint matching) resilient to missing hash functions. In certain environments such as in a FIPS enabled system, certain algorithms such as md5 may be unavailable.

Misc

• Backport "Use is for type comparisons" https://github.com/aiortc/aioquic/commit/5c55e0c75d414ab171a09a732c2d8aaf6f178c05
• Postpone annotations parsing with from __future__ import annotations everywhere in order to simplify type annotations.

1.0.9 (2024-08-17)

Changed

• Bump aws-lc-rs from version 1.7.3 to 1.8.1
• Bump rustls from 0.23.8 to 0.23.12

Fixed

• Incomplete Cargo manifest that can lead to a build error on specific platforms https://github.com/jawah/qh3/issues/37

Added

• Explicit support for Python 3.13

1.0.8 (2024-06-13)

Added

• Support for Windows ARM64 pre-built wheel in CD pipeline.

Changed

• Lighter build requirements by refactoring our Rust / Cargo dependencies.

1.0.7 (2024-05-08)

Fixed

• Decryption error after receiving long (quic) header that required key derivation.

1.0.6 (2024-05-06)

Changed

• Further improved the reliability of the qpack encoder/decoder.

1.0.5 (2024-05-04)

Fixed

• Qpack encoder / decoder failure due to unfed stream data.

1.0.4 (2024-04-23)

Changed

• Buffer management has been migrated over to Rust in order to improve the overall performance.

Misc

• MacOS universal2 wheels are available

1.0.3 (2024-04-20)

Fixed

• setting assert_hostname to False triggered an error when the peer certificate contained at least one IP in subject alt names.

1.0.2 (2024-04-20)

Fixed

• qpack encoder/decoder blocking state in a rare condition.
• missing (a default) NullHandler for quic and http3 loggers causing a StreamHandler to write into stderr.
• setting assert_hostname to False did not disable hostname verification / match with given certificate.

Changed

• Updated rustls to v0.23.5

1.0.1 (2024-04-19)

Fixed

• PyO3 unsendable classes constraint has been relaxed. qh3 is not thread-safe and you should take appropriate measures in a concurrent environment.

Added

• Exposed CipherSuite and SessionTicket classes in the top-level import.

Misc

• Exposed a x509 helper to make for cryptography dependency removal, solely for Niquests usage.

1.0.0 (2024-04-18)

Removed

• Breaking: Dependency on cryptography along with the indirect dependencies on cffi and pycparser.
• Breaking: H0Connection class that was previously deprecated. Use either urllib3-future or niquests instead.
• Breaking: Draft support for QUIC and H3 protocols.
• Breaking: RSA_PKCS1_SHA1 signature algorithm due to its inherent risk dealing with the unsafe SHA1.
• Breaking: ED448/X448 signature and private key are no longer supported due to its absence in aws-lc-rs.
• Breaking: You may no longer pass certificates (along with private keys) as object that comes from cryptography. You have to encode them into PEM format.

Changed

• ls-qpack binding integration upgraded to v2.5.4 and migrated to Rust.
• cryptographic bindings are rewritten in Rust using the PyO3 SDK, the underlying crypto library is aws-lc-rs 1.6.4
• certificate chain control with dns name matching is delegated to rustls instead of previously half-vendored (py)OpenSSL (X509Store).

Added

• Exposed a public API for qh3 (top-level import).
• SECP384R1 key exchange algorithm as a supported group by default to make for the X448 removal.
• SECP521R1 key exchange algorithm is also supported but not enabled by default per standards (NSA Suite B) recommendations.

Misc

• Noticeable performance improvement and memory safety thanks to the Rust migration. We tried to leverage pure Rust binding whenever we could do it safely.
• Example scripts are adapted for this major version.
• Using maturin as the build backend.
• Published new compatible architectures for pre-built wheels.
• Initial MSRV 1.75+

If you rely on one aspect of enumerated breaking changes, please pin qh3 to exclude this major (eg. >=0.15,<1) and inform us on how this release affected your program(s). We will listen.

The semantic versioning will be respected excepted for the hazardous materials.

0.15.1 (2023-03-21)

Fixed

• Improved stream write scheduling. (upstream patch https://github.com/aiortc/aioquic/pull/475)

Misc

• CI now prepare a complete sdist with required vendors
• aarch64 linux is now served

0.15.0 (2023-02-01)

Changed

• Highly simplified _crypto module based on upstream work https://github.com/aiortc/aioquic/pull/457
• Bump upper bound cryptography version to 42.x

Fixed

• Mitigate deprecation originating from cryptography about datetime naïve timezone.

0.14.0 (2023-11-11)

Changed

• Converted our Buffer implementation to native Python instead of C as performance is better thanks to CPython internal optimizations

Fixed

• Addressed performance concerns when attributing new stream ids
• The retry token was based on a weak key

Added

• StopSendingReceived event
• Property open_outbound_streams in QuicConnection
• Property max_concurrent_bidi_streams in QuicConnection
• Property max_concurrent_uni_streams in QuicConnection
• Method get_cipher in QuicConnection
• Method get_peercert in QuicConnection
• Method get_issuercerts in QuicConnection

Added

• Support for in-memory certificates (client/intermediary) via Configuration.load_cert_chain(..)

Removed

• (internal) Unused code in private _vendor.OpenSSL

Changed

• All INFO logs entries are downgraded to DEBUG

Removed

• Certifi will no longer be used if present in the environment. Use jawah/wassima as a super replacement.

Deprecated

• H0Connection will be removed in the 1.0 milestone. Use HTTP Client Niquests instead.

Fixed

• QuicConnection ignored verify_hostname context option (PR #16 by @doronz88)

Added

• Support for QUIC mTLS on the client side (PR #13 by @doronz88)

Added

• Toggle for hostname verification in Configuration

Changed

• Hostname verification can be done independently of certificate verification

Added

• Support for certificate fingerprint matching

Fixed

• datetime.utcnow deprecation

Changed

• commonName is no longer checked by default

Added

• Support for "IP Address" as subject alt name in certificate verifications

Removed

• Dependency on OpenSSL development headers

Changed

• Crypto module relies on cryptography OpenSSL binding instead of our own copy

Added

• Explicit support for PyPy

Version 0.10.0

Removed

• Dependency on pyOpenSSL
• Dependency on certifi
• Dependency on pylsqpack

Changed

• Vendored pyOpenSSL.crypto for the certificate verification chain (X590Store)
• Vendored pylsqpack, use v1.0.3 from upstream and make module abi3 compatible
• The module _crypto and _buffer are abi3 compatible
• The whole package is abi3 ready
• certifi ca bundle is loaded only if present in the current environment (behavior will be removed in v1.0.0)

Fixed

• Mitigate ssl.match_hostname deprecation by porting urllib3 match_hostname
• Mimic ssl load_default_cert into the certification chain verification