{"cve":"CVE-2026-67422","nvd":{"published":"2026-08-06T22:18:21.600","modified":"2026-10-24T16:10:00.153","status":"Awaiting Analysis","description":"pymdown-extensions is a collection of extensions for the Python Markdown library. In versions up to and including 11.0, four inline processors (caret, tilde, betterem, and magiclink) use regular expressions whose content groups can partition a run of delimiter characters in exponentially many ways, causing catastrophic backtracking. As a result, a single untrusted Markdown line under 50 bytes rendered with markdown.markdown() in each extension's default configuration drives the rendering thread into unbounded CPU usage that grows exponentially with input length, enabling an unauthenticated remote attacker who can submit Markdown to cause denial of service. The exposure is concrete for web applications that render user-supplied Markdown (comments, wikis, issue bodies, live preview), including any app using pymdownx.extra which bundles the vulnerable betterem default, as well as hosted docs/CI systems that build untrusted Markdown. The issue has been fixed in version 11.0.1.","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-1333"],"references":["https://github.com/facelessuser/pymdown-extensions/commit/c68498598d7b13011bb4571350b6e3612a4ce44b","https://github.com/facelessuser/pymdown-extensions/security/advisories/GHSA-gm37-52c6-37mw","https://github.com/facelessuser/pymdown-extensions/security/advisories/GHSA-gm37-52c6-37mw"],"products":[],"source":"nvd","synced_at":"2026-10-24T16:53:34.184483516+00:00"},"epss":{"cve":"CVE-2026-67422","score":0.00608,"percentile":0.48769,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-gm37-52c6-37mw","url":"https://osv.dev/vulnerability/GHSA-gm37-52c6-37mw","summary":"pymdown-extensions: exponential-backtracking ReDoS in caret, tilde, betterem, and magiclink inline processors","modified":"2026-09-10T03:51:14.089911270Z","packages":[{"ecosystem":"PyPI","name":"pymdown-extensions","purl":"pkg:pypi/pymdown-extensions","ranges":["<11.0.1"],"fixed":["11.0.1"]}]},{"id":"PYSEC-2026-3654","url":"https://osv.dev/vulnerability/PYSEC-2026-3654","summary":"pymdown-extensions: exponential-backtracking ReDoS in caret, tilde, betterem, and magiclink inline processors","modified":"2026-08-10T11:30:11.950190497Z","packages":[{"ecosystem":"PyPI","name":"pymdown-extensions","purl":"pkg:pypi/pymdown-extensions","ranges":["<11.0.1"],"fixed":["11.0.1"]}]}],"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."]}