{"schema_version":"1.7.5","id":"PYSEC-2026-3455","published":"2026-07-14T17:17:14.750Z","modified":"2026-07-22T11:00:08.839373736Z","aliases":["CVE-2026-59884","GHSA-m4p7-r5rc-7g4j"],"details":"pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the BER decoder shared by the CER and DER codecs parses long-form tags by accumulating continuation octets without an upper bound on the tag ID size, allowing a crafted input to force construction of an arbitrarily large integer with CPU cost growing quadratically and to trigger unhandled ValueError exceptions in Python 3.11+ error formatting paths. Any application decoding untrusted BER, CER, or DER input is affected. This issue is fixed in version 0.6.4.","affected":[{"package":{"name":"pyasn1","ecosystem":"PyPI","purl":"pkg:pypi/pyasn1"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.6.4"}]}],"versions":["0.0.10a","0.0.11a","0.0.12a","0.0.13","0.0.13a","0.0.13b","0.0.6a","0.0.9a","0.1.1","0.1.2","0.1.3","0.1.4","0.1.5","0.1.6","0.1.7","0.1.8","0.1.9","0.2.1","0.2.2","0.2.3","0.3.1","0.3.2","0.3.3","0.3.4","0.3.5","0.3.6","0.3.7","0.4.1","0.4.2","0.4.3","0.4.4","0.4.5","0.4.6","0.4.7","0.4.8","0.5.0","0.5.1","0.6.0","0.6.1","0.6.2","0.6.3"],"ecosystem_specific":{},"database_specific":{"source":"https://github.com/pypa/advisory-database/blob/main/vulns/pyasn1/PYSEC-2026-3455.yaml"}}],"references":[{"type":"ADVISORY","url":"https://github.com/pyasn1/pyasn1/releases/tag/v0.6.4"},{"type":"ADVISORY","url":"https://github.com/pyasn1/pyasn1/security/advisories/GHSA-m4p7-r5rc-7g4j"},{"type":"FIX","url":"https://github.com/pyasn1/pyasn1/commit/628e36ecbb5277a3f01572ce418ef54271b165a5"}],"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}