# CVE-2026-111759: markdown-it: Quadratic complexity in smartquotes with unmatched closing quotes

> Attackers can cause denial of service in applications using markdown-it with typographer enabled by submitting crafted Markdown input.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 19 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** CLSA-2026-1792518269, CLSA-2026-1792523617, CLSA-2026-1792575285, CLSA-2026-1792587416, CLSA-2026-1792596594, CLSA-2026-1793102413, DEBIAN-CVE-2026-111759, ECHO-f728-a8df-aba7, GHSA-r7fv-28h4-cvq7, ROOT-APP-NPM-CVE-2026-111759, UBUNTU-CVE-2026-111759

## What is CVE-2026-111759?

CVE-2026-111759 is a high-severity denial of service vulnerability in markdown-it, published on 19 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

markdown-it is a Markdown parser. Prior to 14.3.2 and 15.0.2, when typographer: true is enabled, specially crafted Markdown can cause quadratic processing time in the smartquotes rule, potentially leading to denial of service in applications processing untrusted input. Many opening double quotes followed by unmatched closing single quotes cause repeated scans of the entire opener stack. The same issue occurs with the quote types reversed. The default configuration (typographer: false) is not affected, but this option is enabled with high probability. This issue is fixed in versions 14.3.2 and 15.0.2.

Weakness: CWE-407 (Inefficient Algorithmic Complexity), CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2026-111759?

4 open source packages ship an affected version, including markdown-it.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `markdown-it` | npm | All versions | 14.3.2 |
| `markdown-it` | npm | All versions | 14.3.2 |
| `markdown-it` | npm | From 15.0.0 | 15.0.2 |
| `markdown-it` | npm | From 15.0.0 | 15.0.2 |

## How do I fix CVE-2026-111759?

Upgrade markdown-it to a fixed version for your release line: 14.3.2 or 15.0.2.

## Is CVE-2026-111759 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-111759 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-111759 and fix it if it is affected.

What it is: CVE-2026-111759 is a high-severity denial of service vulnerability in markdown-it, published on 19 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-111759 exists.

Affected packages and fixed versions:
- markdown-it (npm): affected all versions; fixed in 14.3.2
- markdown-it (npm): affected all versions; fixed in 14.3.2
- markdown-it (npm): affected from 15.0.0; fixed in 15.0.2
- markdown-it (npm): affected from 15.0.0; fixed in 15.0.2

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-2026-111759/ (Markdown: https://insights.sbomify.com/CVE-2026-111759/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-111759
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-111759
- OSV: https://osv.dev/vulnerability/CVE-2026-111759

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-111759/
Summaries are generated and may contain mistakes; the official description above is the record.