{"cve":"CVE-2021-20270","nvd":{"published":"2021-03-23T17:15:13.827","modified":"2026-06-17T03:33:34.817","status":"Modified","description":"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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5},"cwes":["CWE-835"],"references":["https://bugzilla.redhat.com/show_bug.cgi?id=1922136","https://lists.debian.org/debian-lts-announce/2021/05/msg00003.html","https://lists.debian.org/debian-lts-announce/2021/05/msg00006.html","https://www.debian.org/security/2021/dsa-4889","https://www.oracle.com/security-alerts/cpuoct2021.html"],"products":["debian:debian_linux","fedoraproject:fedora","pygments:pygments","redhat:enterprise_linux","redhat:openshift_container_platform","redhat:openstack_platform","redhat:software_collections"],"source":"nvd","synced_at":"2026-10-19T21:15:50.279857260+00:00"},"epss":{"cve":"CVE-2021-20270","score":0.02759,"percentile":0.86261,"date":"2026-11-01"},"kev":null,"osv":[{"id":"GHSA-9w8r-397f-prfh","url":"https://osv.dev/vulnerability/GHSA-9w8r-397f-prfh","summary":"Infinite Loop in Pygments","modified":"2024-10-14T18:43:36.784789Z","packages":[{"ecosystem":"PyPI","name":"pygments","purl":"pkg:pypi/pygments","ranges":[">=1.5 <2.7.4"],"fixed":["2.7.4"]}]},{"id":"PYSEC-2021-140","url":"https://osv.dev/vulnerability/PYSEC-2021-140","summary":"","modified":"2023-11-08T04:04:36.317980Z","packages":[{"ecosystem":"PyPI","name":"pygments","purl":"pkg:pypi/pygments","ranges":[">=1.5 <2.7.4"],"fixed":["2.7.4"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}