# markdown-it: Quadratic-time rendering of a single multi-line link reference definition with default options (regression since 14.0)

Advisory record · `GHSA-gfr2-rv44-r23c`

- **Identifiers:** `GHSA-gfr2-rv44-r23c` · `CVE-2026-111758`
- **State:** Confirmed
- **Severity:** CVSS 7.5 High
- **Critical:** No
- **Weakness (CWE):** [CWE-400](https://cwe.mitre.org/data/definitions/400.html) · [CWE-407](https://cwe.mitre.org/data/definitions/407.html)
- **Tags:** [Denial of service](https://agentprime.io/advisories/tag/dos.md)
- **Published:** 20 Oct 2026
- **Updated:** 20 Oct 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 20 Oct 2026, 20:28 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `markdown-it` (npm): affected `>=14.1.0, <14.3.3 || >=15.0.0, <15.0.3`; fixed in `14.3.3`, `15.0.3`

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> The markdown-it npm package from 14.1.0 before 14.3.3, and from 15.0.0 before 15.0.3, is affected. An attacker who can submit Markdown text can send a link reference definition whose label or title is never closed and spans many lines; with default options, rendering takes quadratic time and can block the server's event loop. Upgrade to 14.3.3 or 15.0.3.

Written 31 Oct 2026.

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 7.5 High, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0055, the 46th percentile, on 9 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 13:33 UTC: First seen by agentprime
- 31 Oct 2026, 13:33 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-gfr2-rv44-r23c)

## Sources

- [GitHub Advisory Database: GHSA-gfr2-rv44-r23c](https://github.com/advisories/GHSA-gfr2-rv44-r23c)
- [OSV: GHSA-gfr2-rv44-r23c](https://osv.dev/vulnerability/GHSA-gfr2-rv44-r23c)
- <https://github.com/markdown-it/markdown-it/security/advisories/GHSA-gfr2-rv44-r23c>
- <https://github.com/markdown-it/markdown-it/commit/48fbc465812c440020c663f040ab22deaf8f1eca>
- <https://github.com/markdown-it/markdown-it/commit/d99f48839d37af6fd8a2617516c43dab90755503>
- <https://github.com/markdown-it/markdown-it>
- <https://github.com/markdown-it/markdown-it/releases/tag/14.3.3>
- <https://github.com/markdown-it/markdown-it/releases/tag/15.0.3>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-gfr2-rv44-r23c>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-gfr2-rv44-r23c/>. Everything for agents: <https://agentprime.io/llms.txt>.