Answer in brief
CVE-2026-67422 records a High severity (CVSS 7.5) vulnerability in pymdown-extensions: Exponential-backtracking ReDoS in caret, tilde, betterem, and magiclink inline processors. The current sources do not mark it as known exploited. The current feed maps facelessuser/pymdown-extensions (generic), pymdown-extensions (pip), pymdown-extensions (pypi). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 7.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps facelessuser/pymdown-extensions (generic), pymdown-extensions (pip), pymdown-extensions (pypi). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| facelessuser/pymdown-extensionsgeneric | <11.0.1 | 11.0.1 |
| pymdown-extensionspip | <=11.0.0 | 11.0.1 |
| pymdown-extensionspypi | >=0 <11.0.1 | 11.0.1 |
Published upstream
Aug 6, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 24, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 6, 2026
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.
Quoted source text, attributed separately from HOL analysis.