CVE-2026-86429

HIGHPre-NVD 7.57.5—
EchelonGraph scoreHIGH confidence

Score 7.5 from GitHub Security Advisory (severity: HIGH) published 2026-09-07. a secondary CVSS source baseline 7.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this week
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.5Exploit: None knownExposed: 0

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

The league/commonmark (thephpleague/commonmark) library in versions >= 1.5.0 and < 2.9.1 contains quadratic parsing complexity in its SmartPunctExtension and AttributesExtension. When either extension is explicitly registered on the Environment (they are not enabled by default and are excluded from the standard CommonMark and GitHub-Flavored Markdown converters), an unauthenticated attacker can submit small, specially crafted Markdown documents — such as text alternating with unpaired quotes, contiguous runs of block-level attribute blocks, or repeated class attributes — to trigger disproportionate CPU consumption and cause a denial of service. Fixed in 2.9.1.

CVSS v3
7.5
EG Score
7.5(high)
EG Risk
38(Track)
EG Risk 38/100SSVC: Track

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%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
22%
KEV
Not listed

Published

September 7, 2026

Last Modified

September 9, 2026

Advisory Details (2)

Auto-updated Sep 7, 2026
Patch available. Sources: github.
generic

commonmark before 2.9.1 Denial of Service via SmartPunct and Attributes | Advisories | VulnCheck

https://www.vulncheck.com/advisories/commonmark-before-2.9.1-denial-of-service-via-smartpunct-and-attributes
github Patch Available

Denial of service in the SmartPunct and Attributes extensions · Advisory · thephpleague/commonmark · GitHub

Affected: 2.9.0.

https://github.com/thephpleague/commonmark/security/advisories/GHSA-jjv6-8j6v-6j52

Vendor Advisories for CVE-2026-86429(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
php-league-commonmark2.10.0-1 ... 2.9.0-1 (23 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
php-league-commonmark2.10.0-1 ... 2.9.0-1 (11 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
php-league-commonmark2.7.0-1 ... 2.9.0-1 (9 versions)2.10.0-1—
Packagist(1)
PackageVulnerable rangeFixed inDependents
league/commonmark1.5.0 ... 2.9.0 (66 versions)2.9.1—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 27× in last 7d / 48× 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. 2026-09-18 22:00 UTCEG score recompute
  2. 2026-09-18 22:00 UTCGHSA enrichment
  3. 2026-09-18 19:28 UTCEPSS rescore
  4. 2026-09-18 11:00 UTCGHSA enrichment
  5. 2026-09-18 00:00 UTCEG score recompute
  6. 2026-09-18 00:00 UTCGHSA enrichment
  7. 2026-09-17 19:32 UTCEPSS rescore
  8. 2026-09-17 13:00 UTCGHSA enrichment
  9. 2026-09-17 01:39 UTCGHSA enrichment
  10. 2026-09-16 14:39 UTCEG score recompute
  11. 2026-09-16 14:39 UTCGHSA enrichment
  12. 2026-09-16 14:09 UTCEPSS rescore
  13. 2026-09-16 05:15 UTCEPSS rescore
  14. 2026-09-16 03:37 UTCGHSA enrichment
  15. 2026-09-15 16:37 UTCGHSA enrichment
  16. 2026-09-15 05:33 UTCEG score recompute
  17. 2026-09-15 05:32 UTCGHSA enrichment
  18. 2026-09-15 03:12 UTCEPSS rescore
  19. 2026-09-15 03:12 UTCEPSS rescore
  20. 2026-09-14 18:21 UTCGHSA enrichment
  21. 2026-09-14 07:05 UTCGHSA enrichment
  22. 2026-09-13 20:05 UTCEG score recompute
  23. 2026-09-13 20:05 UTCGHSA enrichment
  24. 2026-09-13 09:05 UTCGHSA enrichment
  25. 2026-09-12 22:05 UTCEG score recompute
Show 23 more
  1. 2026-09-12 22:05 UTCGHSA enrichment
  2. 2026-09-12 11:05 UTCGHSA enrichment
  3. 2026-09-11 23:54 UTCEG score recompute
  4. 2026-09-11 23:54 UTCGHSA enrichment
  5. 2026-09-11 14:53 UTCEPSS rescore
  6. 2026-09-11 14:53 UTCEPSS rescore
  7. 2026-09-11 12:54 UTCEG score recompute
  8. 2026-09-11 12:53 UTCGHSA enrichment
  9. 2026-09-11 01:53 UTCGHSA enrichment
  10. 2026-09-10 14:53 UTCEG score recompute
  11. 2026-09-10 14:53 UTCGHSA enrichment
  12. 2026-09-10 03:54 UTCGHSA enrichment
  13. 2026-09-09 16:52 UTCGHSA enrichment
  14. 2026-09-09 07:12 UTCEG score recompute
  15. 2026-09-09 07:12 UTCGHSA enrichment
  16. 2026-09-08 22:01 UTCEPSS rescore
  17. 2026-09-08 20:13 UTCGHSA enrichment
  18. 2026-09-08 11:27 UTCGHSA enrichment
  19. 2026-09-08 00:28 UTCEG score recompute
  20. 2026-09-08 00:28 UTCGHSA enrichment
  21. 2026-09-07 13:28 UTCEG score recompute
  22. 2026-09-07 12:58 UTCEG score recompute
  23. 2026-09-07 12:56 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-86429?
CVE-2026-86429 is a high vulnerability published on September 7, 2026. The league/commonmark (thephpleague/commonmark) library in versions >= 1.5.0 and < 2.9.1 contains quadratic parsing complexity in its SmartPunctExtension and AttributesExtension. When either extension is explicitly registered on the Environment (they are not enabled by default and are excluded from…
When was CVE-2026-86429 disclosed?
CVE-2026-86429 was first published in the National Vulnerability Database on September 7, 2026, with the most recent update on September 9, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-86429 actively exploited?
CVE-2026-86429 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 78.1% of all scored CVEs.
What is the CVSS score of CVE-2026-86429?
CVE-2026-86429 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-86429?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-86429, 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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