Description
markdown-it is a Markdown parser. Prior to 14.3.3 and 15.0.3, when the html option or commonmark preset is enabled and the constructs occur inside a paragraph, attacker-controlled Markdown containing repeated unterminated inline HTML comments, processing instructions, declarations, or CDATA sections reaches src/rules_inline/html_inline.ts. Its HTML_TAG_RE match searches the remaining suffix for the appropriate terminator; when no terminator is present, parsing advances to the next opener and repeats the match over overlapping input, causing quadratic processing and denial of service through event-loop blocking or an unresponsive browser main thread. HTML blocks and the default HTML-disabled configuration are not affected by these payloads. This issue is fixed in versions 14.3.3 and 15.0.3.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| markdown-it | markdown-it | >= 15.0.0, < 15.0.3, < 14.3.3 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | node-markdown-it | No fix yet | — |
| Debian 13 | node-markdown-it | No fix yet | — |
| Debian 12 | node-markdown-it | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | node-markdown-it | No fix yet | — |
| Ubuntu 26.04 LTS | node-markdown-it | No fix yet | — |
| Ubuntu 24.04 LTS | node-markdown-it | No fix yet | — |
| Ubuntu 22.04 LTS | node-markdown-it | No fix yet | — |
Wolfi
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Wolfi rolling | renovate | 44.176.1-r0 | — |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| npm | markdown-it | < 14.3.3 | 14.3.3 | GHSA-vfgh-jcmw-g37q |
| npm | markdown-it | >= 15.0.0, < 15.0.3 | 15.0.3 | GHSA-vfgh-jcmw-g37q |
References
- https://github.com/markdown-it/markdown-it/security/advisories/GHSA-vfgh-jcmw-g37q
- https://github.com/markdown-it/markdown-it/commit/928bc8c11ded60181c0e7fc5aa954eec582e8e79
- https://github.com/markdown-it/markdown-it/commit/d99f48839d37af6fd8a2617516c43dab90755503
- https://github.com/markdown-it/markdown-it/releases/tag/14.3.3
- https://github.com/markdown-it/markdown-it/releases/tag/15.0.3