CVE-2026-119194

NameCVE-2026-119194
Descriptionpyasn1 is a generic ASN.1 library for Python. From 0.3.3 until 0.6.5, schemaless container decoding stores every decoded component's TagSet in a growing set even though only one-versus-multiple tag types must be distinguished. Attacker-controlled BER, CER, or DER input contains many distinct long tag IDs whose TagSet hashes collide. Each later set insertion compares against an increasing number of earlier colliding tags in ConstructedPayloadDecoderBase._decodeComponentsSchemaless, producing quadratic CPU work while decoded values and order remain valid. Repeated inputs can exhaust decoder CPU and reduce service availability. This issue is fixed in version 0.6.5.
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
pyasn1 (PTS)bookworm0.4.8-3+deb12u2vulnerable
bookworm (security)0.4.8-3+deb12u3vulnerable
trixie0.6.1-1+deb13u3vulnerable
trixie (security)0.6.1-1+deb13u2vulnerable
forky, sid0.6.4-1vulnerable

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

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
pyasn1source(unstable)(unfixed)

Notes

https://github.com/pyasn1/pyasn1/security/advisories/GHSA-fm9c-5rcf-2q5p
Fixed by: https://github.com/pyasn1/pyasn1/commit/a36e3a3d067148d26197a6b7221fd0e2cde9cc86 (v0.6.5)

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