CVE-2026-40170

NameCVE-2026-40170
Descriptionngtcp2 is a C implementation of the IETF QUIC protocol. In versions prior to 1.22.1, ngtcp2_qlog_parameters_set_transport_params() serializes peer transport parameters into a fixed 1024-byte stack buffer without bounds checking. When qlog is enabled, a remote peer can send sufficiently large transport parameters during the QUIC handshake to cause writes beyond the buffer boundary, resulting in a stack buffer overflow. This affects deployments that enable the qlog callback and process untrusted peer transport parameters. This issue has been fixed in version 1.22.1. If developers are unable to immediately upgrade, they can disable the qlog on client.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
ngtcp2 (PTS)bookworm0.12.1+dfsg-1vulnerable
trixie1.11.0-1vulnerable
forky, sid1.21.0-1vulnerable

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
ngtcp2source(unstable)(unfixed)

Notes

https://github.com/ngtcp2/ngtcp2/security/advisories/GHSA-f523-465f-8c8f
Fxied by: https://github.com/ngtcp2/ngtcp2/commit/708a7640c1f48fb8ffb540c4b8ea5b4c1dfb8ee5 (v1.22.1)

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