{"id":"CVE-2021-20270","aliases":["GHSA-9w8r-397f-prfh","PYSEC-2021-140"],"url":"https://o3.security/vulnerability/CVE-2021-20270","summary":"Infinite Loop in Pygments","details":"An infinite loop in SMLLexer in Pygments versions 1.5 to 2.7.3 may lead to denial of service when performing syntax highlighting of a Standard ML (SML) source file, as demonstrated by input that only contains the \"exception\" keyword.","published":"2021-03-23T17:15:13.827Z","modified":"2026-08-22T18:49:58.976704237Z","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"PyPI","name":"pygments","fixedVersion":"2.7.4"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://lists.debian.org/debian-lts-announce/2021/05/msg00006.html"},{"type":"ADVISORY","url":"https://www.debian.org/security/2021/dsa-4889"},{"type":"ADVISORY","url":"https://www.oracle.com/security-alerts/cpuoct2021.html"},{"type":"ADVISORY","url":"https://lists.debian.org/debian-lts-announce/2021/05/msg00003.html"},{"type":"FIX","url":"https://bugzilla.redhat.com/show_bug.cgi?id=1922136"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-22T18:49:58.976704237Z"}}