{"id":"CVE-2026-119196","state":"PUBLISHED","title":"pyasn1: Quadratic CPU consumption in constructed BIT STRING decoding","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.","publishedAt":"2026-10-29T19:44:46.031Z","updatedAt":"2026-10-29T19:44:46.031Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"GitHub_M"},"assigner":"GitHub_M","products":["pyasn1 pyasn1"],"affected":[{"vendor":"pyasn1","product":"pyasn1","versions":[{"version":"< 0.6.5","status":"affected"}]}],"references":["https://github.com/pyasn1/pyasn1/security/advisories/GHSA-2qm8-x737-gmw5","https://github.com/pyasn1/pyasn1/pull/132","https://github.com/pyasn1/pyasn1/commit/73ba7b043cc7e92cb37f16f2c955bff93b0e6f6c","https://github.com/pyasn1/pyasn1/releases/tag/v0.6.5"],"weaknesses":["CWE-407"],"ingestedAt":"2026-10-29T20:14:45.636Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/119xxx/CVE-2026-119196.json","commit":"f3256dbff015d5005201759d42bdccb6679ce6d3","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-119196","state":"PUBLISHED","datePublished":"2026-10-29T19:44:46.031Z","dateUpdated":"2026-10-29T19:44:46.031Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-10-29T16:04:48.728Z"},"containers":{"cna":{"title":"pyasn1: Quadratic CPU consumption in constructed BIT STRING decoding","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"pyasn1","product":"pyasn1","versions":[{"version":"< 0.6.5","status":"affected"}]}],"references":[{"url":"https://github.com/pyasn1/pyasn1/security/advisories/GHSA-2qm8-x737-gmw5","name":"https://github.com/pyasn1/pyasn1/security/advisories/GHSA-2qm8-x737-gmw5","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/pyasn1/pyasn1/pull/132","name":"https://github.com/pyasn1/pyasn1/pull/132","tags":["x_refsource_MISC"]},{"url":"https://github.com/pyasn1/pyasn1/commit/73ba7b043cc7e92cb37f16f2c955bff93b0e6f6c","name":"https://github.com/pyasn1/pyasn1/commit/73ba7b043cc7e92cb37f16f2c955bff93b0e6f6c","tags":["x_refsource_MISC"]},{"url":"https://github.com/pyasn1/pyasn1/releases/tag/v0.6.5","name":"https://github.com/pyasn1/pyasn1/releases/tag/v0.6.5","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":7.5,"baseSeverity":"HIGH","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-407","lang":"en","description":"CWE-407: Inefficient Algorithmic Complexity","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-10-29T19:44:46.031Z"},"source":{"advisory":"GHSA-2qm8-x737-gmw5","discovery":"UNKNOWN"}}}}}