CVE-2026-119196

NameCVE-2026-119196
Descriptionpyasn1 is a generic ASN.1 library for Python. Prior to 0.6.5, constructed BIT STRING decoding repeatedly shifts and copies the complete bit value accumulated from earlier fragments. Attacker-controlled BER or CER input contains many constructed BIT STRING fragments; schema-driven DER also accepts a definite-length constructed BIT STRING. BitStringPayloadDecoder repeatedly calls BitString.fromOctetString with the prior bitString as prepend, shifting an ever-growing SizedInteger for each fragment and causing quadratic work. Large fragmented values can exhaust CPU during decode() without requiring later conversion or formatting. 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-2qm8-x737-gmw5
Fixed by: https://github.com/pyasn1/pyasn1/commit/73ba7b043cc7e92cb37f16f2c955bff93b0e6f6c (v0.6.5)

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