{"id":"CVE-2026-59884","summary":"pyasn1 BER/CER/DER decoder denial of service via unbounded long-form tag IDs","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.","aliases":["GHSA-m4p7-r5rc-7g4j"],"modified":"2026-07-17T03:42:02.056647803Z","published":"2026-07-14T16:41:10.277Z","database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-400"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/59xxx/CVE-2026-59884.json"},"references":[{"type":"WEB","url":"https://github.com/pyasn1/pyasn1/releases/tag/v0.6.4"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/59xxx/CVE-2026-59884.json"},{"type":"ADVISORY","url":"https://github.com/pyasn1/pyasn1/security/advisories/GHSA-m4p7-r5rc-7g4j"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-59884"},{"type":"FIX","url":"https://github.com/pyasn1/pyasn1/commit/628e36ecbb5277a3f01572ce418ef54271b165a5"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/pyasn1/pyasn1","events":[{"introduced":"0"},{"fixed":"628e36ecbb5277a3f01572ce418ef54271b165a5"},{"fixed":"72e4803405816c371ed3b2cb4be181c47f038406"}],"database_specific":{"source":["AFFECTED_FIELD","REFERENCES"],"extracted_events":[{"introduced":"0"},{"fixed":"0.6.4"}]}}],"versions":["v0.6.3","v0.6.2","v0.6.1","v0.6.0","v0.5.1","v0.5.0","v0.4.8","v0.4.7","v0.4.6","v0.4.5","v0.4.4","v0.4.3","v0.4.2","v0.4.1","v0.3.7","v0.3.6","v0.3.5","v0.3.4","v0.3.3","v0.3.2","v0.3.1","0.2.3","v0.2.2","v0.2.1"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-59884.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}