{"id":"CVE-2026-119196","published":"2026-10-29T20:17:30.770","lastModified":"2026-10-29T20:17:30.770","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.","cvssScore":7.5,"cvssSeverity":"HIGH","cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cwes":["CWE-407"],"vendors":[],"products":[],"references":[{"url":"https://github.com/pyasn1/pyasn1/commit/73ba7b043cc7e92cb37f16f2c955bff93b0e6f6c","tags":[]},{"url":"https://github.com/pyasn1/pyasn1/pull/132","tags":[]},{"url":"https://github.com/pyasn1/pyasn1/releases/tag/v0.6.5","tags":[]},{"url":"https://github.com/pyasn1/pyasn1/security/advisories/GHSA-2qm8-x737-gmw5","tags":[]}],"exploitRefs":[{"url":"https://github.com/pyasn1/pyasn1/commit/73ba7b043cc7e92cb37f16f2c955bff93b0e6f6c","tags":[]},{"url":"https://github.com/pyasn1/pyasn1/pull/132","tags":[]},{"url":"https://github.com/pyasn1/pyasn1/releases/tag/v0.6.5","tags":[]},{"url":"https://github.com/pyasn1/pyasn1/security/advisories/GHSA-2qm8-x737-gmw5","tags":[]}],"hasPoc":true,"ai":null}