CVE-2026-86428 json
commonmark 1.5.0 before 2.10.0 Denial of Service via Attributes
published 2026-09-01 2 mo ago modified 2026-10-08 32 d ago also GHSA-8rr7-cvq3-gmfh , EUVD-2026-72386
- cvss
- 7.5
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.5%
- EPSS 0.5% chance of exploitation in 30 days, percentile 42%
- public exploits
- 0
- none known
Summary
commonmark versions from 1.5.0 before 2.10.0 contain a denial of service vulnerability in the AttributesExtension when processing distinctly-named attributes. Attackers can submit Markdown with numerous distinct attribute names to cause quadratic-time attribute merging and filtering, consuming disproportionate CPU resources and preventing legitimate requests from completing.
Patch / fix
- packagist league/commonmark 2.10.0
- thephpleague commonmark 2.10.0
- php-league-commonmark Debian 14 2.10.0-1
debian advisories DEBIAN-CVE-2026-86428
CISA SSVC
- Exploitation
- none
- Automatable
- yes
- Technical impact
- partial
- Assessed
- 2 mo ago
Exploit prediction
0.49% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 8.7 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N |
| CNA | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| CNA | 4.0 | 8.7 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
| GitHub | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| packagist | league/commonmark | >=1.5.0, <2.10.0 |
2.10.0 |
Affected products
- thephpleague commonmark
Classification
References
-
github.com
/thephpleague/commonmark/commit/f27eb720972490b5af4dbb635ad8634529faf9f2
web
-
github.com
/thephpleague/commonmark/security/advisories/GHSA-8rr7-cvq3-gmfh
vendor-advisory, web, mitigation
-
vulncheck.com
/advisories/commonmark-1.5.0-before-2.10.0-denial-of-service-via-attributes
third-party-advisory
-
github.com
/thephpleague/commonmark
package
-
github.com
/thephpleague/commonmark/releases/tag/2.10.0
web
Sources
- CVE List CVE-2026-86428
- GitHub Advisory GHSA-8rr7-cvq3-gmfh
- NVD CVE-2026-86428
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.