CVE-2026-119196

CVSS 7.5 (high) · published 2026-10-29

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.

Weakness: CWE-407

Source: NVD CVE-2026-119196

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
• https://github.com/pyasn1/pyasn1/security/advisories/GHSA-2qm8-x737-gmw5

Check your software

Connect an AI agent to the FixLane MCP server or ask the Telegram bot to check what you have installed against incidents with a verified fixed version.