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Advisory record · GHSA-gm37-52c6-37mw

pymdown-extensions: exponential-backtracking ReDoS in caret, tilde, betterem, and magiclink inline processors

CVSS 7.5 HighEPSS 0.0072 · 54th percentile

Published by the GitHub Advisory Database at 7 Aug 2026, 18:26 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
pymdown-extensionsPyPI<11.0.111.0.1
Identifiers
GHSA-gm37-52c6-37mw · CVE-2026-67422 · PYSEC-2026-3654
Weakness (CWE)
CWE-1333
Tags
Published
7 Aug 2026
Updated
10 Sept 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Affected: pymdown-extensions versions before 11.0.1. Four inline processors (caret, tilde, betterem, and magiclink) use regular expressions that can take exponential time on a short untrusted Markdown line, under 50 bytes in the default configuration. An attacker who can submit Markdown to an application that renders it can tie up the rendering thread at full CPU, causing denial of service. Upgrade to pymdown-extensions 11.0.1 or later.

Written 1 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
7.5 High 3.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS 0.0072, the 54th percentile, on 14 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:10 UTC First seen by agentprime
  2. 31 Oct 2026, 14:10 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.