commonmark 1.5.0 before 2.10.0 Denial of Service via Attributes
Priority MEDIUM 44CWE-407Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-407.
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.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00493 42nd percentileScored 2026-11-07
Fix Fixed commonmark (thephpleague): 2.10.0
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| thephpleague | commonmark | 1.5.0 to before 2.10.0 | 2.10.0 | Patch available | CNA |
- commonmark Vendorthephpleague Affected 1.5.0 to before 2.10.0 Fixed in 2.10.0 Patch available CNA
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:thephpleague:commonmark:*:*:*:*:*:*:*:* | 1.5.0 to before 2.10.0 | Vulnerable | thephpleague |
- cpe:2.3:a:thephpleague:commonmark:*:*:*:*:*:*:*:* Versions 1.5.0 to before 2.10.0 Vulnerable ·thephpleague
Remediation
- Fix · CNA commonmark (thephpleague) Fixed in 2.10.0
Timeline
- 2026-10-02 Threatist record created from CVE-2026-86428
- 2026-10-03 Alias added: GHSA-8h74-w38m-j62j
References
More thephpleague Commonmark vulnerabilities
- TI-2026-59138 league/commonmark before 2.9.1 Denial of Service via parsing CVSS 4.0HIGH 8.7
- TI-2026-59137 commonmark before 2.9.1 Denial of Service via SmartPunct and Attributes CVSS 4.0HIGH 8.7
- TI-2026-59139 commonmark before 2.9.1 XSS via AttributesExtension form feed bypass CVSS 4.0MEDIUM 6.9
- TI-2026-25753 league/commonmark has an embed extension allowed_domains bypass CVSS 4.0MEDIUM 6.3
- TI-2018-14605 Cross-site scripting (XSS) vulnerability in the PHP League CommonMark library versions… CVSS 3.0MEDIUM 6.1
- TI-2019-07346 Cross-site scripting (XSS) vulnerability in the PHP League CommonMark library before… CVSS 3.0MEDIUM 6.1
Sources
- CVE-2026-86428 · CVE Program
- CVE-2026-86428 · NVD
- FIRST EPSS
- GHSA-8h74-w38m-j62j · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences