# CVE-2026-118694: python-markdown2 through 2.5.5 Denial of Service via Unclosed Inline Link Destinations


- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 28 Oct 2026
- **Updated:** 29 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-118694, GHSA-rgrp-3mvm-5g9j, UBUNTU-CVE-2026-118694

## What is CVE-2026-118694?

CVE-2026-118694 is a high-severity vulnerability in trentm python-markdown2, published on 28 Oct 2026. 

### Official description

python-markdown2 through 2.5.5 contains a denial of service vulnerability that allows remote users to exhaust CPU by submitting Markdown with unclosed inline link destinations. Attackers can submit repeated '[a](' or '![a](' sequences, causing _find_balanced to rescan the remaining document for each link and consume quadratic CPU time.

Weakness: CWE-407 (Inefficient Algorithmic Complexity)

## Which versions are affected by CVE-2026-118694?


## How do I fix CVE-2026-118694?

No fix has been published for CVE-2026-118694 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-118694 being exploited?

There is no known exploitation of CVE-2026-118694 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-118694 and fix it if it is affected.

What it is: CVE-2026-118694 is a high-severity vulnerability in trentm python-markdown2, published on 28 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-118694 in the wild and no public exploit code.

Affected product: trentm python-markdown2. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-118694/ (Markdown: https://insights.sbomify.com/CVE-2026-118694/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-118694
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-118694
- OSV: https://osv.dev/vulnerability/CVE-2026-118694

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-118694/
Summaries are generated and may contain mistakes; the official description above is the record.