# CVE-2026-86433: php-league-commonmark: commonmark versions from 1.5.0 before 2.8.4 contain a denial of service vulnerability in the Attributes extension whe...

CVE-2026-86433 is fixed in php-league-commonmark on 1 platform by DEBIAN-CVE-2026-86433 (version 2.9.0-1), released September 8, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-86433
- Priority: Routine
- CVSS: n/a
- EPSS: 0.0051
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 7, 2026

## Description

commonmark versions from 1.5.0 before 2.8.4 contain a denial of service vulnerability in the Attributes extension where AttributesListener::findTargetAndDirection() performs quadratic-time sibling list scanning. Unauthenticated attackers can submit approximately 32 KB of repeated attribute blocks to cause parsing to take over 5 seconds, exhausting server resources.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | php-league-commonmark Debian 14 | 2.9.0-1 | [DEBIAN-CVE-2026-86433](https://patchblox.com/security/data/fix/linux/debian-cve-2026-86433.md) | Sep 8, 2026 |

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Data as of 2026-11-09T01:18:40Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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