Vulnerability Description
pyasn1 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.
CVSS Score
HIGH
Related Weaknesses (CWE)
References
- https://github.com/pyasn1/pyasn1/commit/73ba7b043cc7e92cb37f16f2c955bff93b0e6f6c
- https://github.com/pyasn1/pyasn1/pull/132
- https://github.com/pyasn1/pyasn1/releases/tag/v0.6.5
- https://github.com/pyasn1/pyasn1/security/advisories/GHSA-2qm8-x737-gmw5
FAQ
What is CVE-2026-119196?
CVE-2026-119196 is a vulnerability with a CVSS score of 7.5 (HIGH). pyasn1 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-controlle...
How severe is CVE-2026-119196?
CVE-2026-119196 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-119196?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.