CVE-2026-67422

HIGHPre-NVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.6%, top 55% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Elevated
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 7.5Exploit: Elevated riskExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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 v3
7.5
EG Score
7.5(medium)
EG Risk
65(Attend)
EG Risk 65/100SSVC: Attend

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity75% × 45%
Exploitation40% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
1%
EPSS %ILE
45%
KEV
Not listed

Published

August 6, 2026

Last Modified

August 7, 2026

Advisory Details (2)

Auto-updated Aug 6, 2026
🔬 Proof of concept available. Patch available. Sources: github, github_commit.
github_commit Patch Available

commit c68498598d7b (facelessuser/pymdown-extensions)

Patch available: facelessuser/pymdown-extensions 11.0.1 (contains commit c68498598d7b)

https://github.com/facelessuser/pymdown-extensions/commit/c68498598d7b13011bb4571350b6e3612a4ce44b
github Patch Available🟡 PoC Available

pymdown-extensions: exponential-backtracking ReDoS in caret, tilde, betterem, and magiclink inline processors · Advisory · facelessuser/pymdown-extensions · GitHub

Affected: 10.16.1): different extensions, different regexes, and a

https://github.com/facelessuser/pymdown-extensions/security/advisories/GHSA-gm37-52c6-37mw

Vendor Advisories for CVE-2026-67422(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(4 across 4 ecosystems)
Debian:12(1)
PackageVulnerable rangeFixed inDependents
pymdown-extensions10.11.2-1 ... 9.5-5 (14 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
pymdown-extensions10.13-1 ... 11.0.1-1 (8 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
pymdown-extensions10.13-1 ... 10.19.1-3 (6 versions)11.0.1-1—
PyPI(1)
PackageVulnerable rangeFixed inDependents
pymdown-extensions1.0.0 ... 9.9.2 (119 versions)11.0.1—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 12× in last 7d / 28× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-08-20 22:56 UTCEPSS rescore
  2. 2026-08-19 20:12 UTCEG score recompute
  3. 2026-08-19 17:04 UTCEPSS rescore
  4. 2026-08-18 17:54 UTCEG score recompute
  5. 2026-08-18 13:48 UTCEPSS rescore
  6. 2026-08-18 02:54 UTCEG score recompute
  7. 2026-08-17 13:47 UTCEPSS rescore
  8. 2026-08-17 00:39 UTCEG score recompute
  9. 2026-08-16 14:56 UTCEPSS rescore
  10. 2026-08-16 11:31 UTCEG score recompute
  11. 2026-08-15 09:16 UTCEG score recompute
  12. 2026-08-15 01:30 UTCEPSS rescore
  13. 2026-08-14 07:00 UTCEG score recompute
  14. 2026-08-13 22:00 UTCEPSS rescore
  15. 2026-08-12 15:33 UTCEG score recompute
  16. 2026-08-12 13:51 UTCEPSS rescore
  17. 2026-08-12 02:25 UTCEG score recompute
  18. 2026-08-11 00:10 UTCEG score recompute
  19. 2026-08-11 00:00 UTCEPSS rescore
  20. 2026-08-09 21:54 UTCEG score recompute
  21. 2026-08-09 13:47 UTCEPSS rescore
  22. 2026-08-08 19:40 UTCEG score recompute
  23. 2026-08-08 16:37 UTCEPSS rescore
  24. 2026-08-07 17:25 UTCEG score recompute
  25. 2026-08-07 17:07 UTCEG score recompute
Show 3 more
  1. 2026-08-06 22:38 UTCEG score recompute
  2. 2026-08-06 22:16 UTCEG score recompute
  3. 2026-08-06 22:15 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-67422?
CVE-2026-67422 is a high vulnerability published on August 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,…
When was CVE-2026-67422 disclosed?
CVE-2026-67422 was first published in the National Vulnerability Database on August 6, 2026, with the most recent update on August 7, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-67422 actively exploited?
CVE-2026-67422 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 54.7% of all scored CVEs.
What is the CVSS score of CVE-2026-67422?
CVE-2026-67422 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-67422?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-67422, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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