CVE-2026-56853

NameCVE-2026-56853
DescriptionWhen a server is configured to support unencrypted HTTP/2, it reads a few bytes from each new connection to see if they contain the HTTP/2 client preface. ReadHeaderTimeout is unexpectedly not being applied when doing this.
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)
Debian Bugs1144340, 1144341, 1144342

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
golang-1.15 (PTS)bullseye1.15.15-1~deb11u4vulnerable
golang-1.19 (PTS)bookworm1.19.8-2vulnerable
golang-1.24 (PTS)trixie1.24.4-1vulnerable
golang-1.25 (PTS)forky, sid1.25.12-1vulnerable
golang-1.26 (PTS)forky, sid1.26.5-1vulnerable
golang-1.27 (PTS)forky, sid1.27~rc2-1vulnerable

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

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
golang-1.15source(unstable)(unfixed)
golang-1.19source(unstable)(unfixed)
golang-1.24source(unstable)(unfixed)
golang-1.25source(unstable)(unfixed)1144342
golang-1.26source(unstable)(unfixed)1144341
golang-1.27source(unstable)(unfixed)1144340

Notes

[trixie] - golang-1.24 <no-dsa> (Minor issue)
https://github.com/golang/go/issues/80205
Fixed by: https://github.com/golang/go/commit/cb4d292bb634ab89a62995f2384df9389d876333 (go1.27rc3)
Fixed by: https://github.com/golang/go/commit/5bbd22ff78daf010c5bd19c466a0c45ac78503d4 (go1.26.6)
Fixed by: https://github.com/golang/go/commit/784132491b1002342026712477725c0d742a53e8 (go1.25.13)

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