# CVE-2024-1899: Showdownjs Denial of Service

> A remote attacker can cause a denial of service in the Showdownjs library via the anchors subparser, affecting applications using this npm package.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 26 Feb 2024
- **Updated:** 1 Aug 2024
- **Also known as:** CLEANSTART-2026-JB83386, GHSA-rmmh-p597-ppvv, MINI-4mm5-73cg-pq28, MINI-4v72-65p8-749h, MINI-6hf8-vh24-7g49, MINI-gv2w-473x-j7xw, MINI-m9xc-j4qc-2hjv, ROOT-APP-NPM-CVE-2024-1899

## What is CVE-2024-1899?

CVE-2024-1899 is a medium-severity denial of service vulnerability in Showdownjs Showdown, published on 26 Feb 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An issue in the anchors subparser of Showdownjs versions <= 2.1.0 could allow a remote attacker to cause denial of service conditions.

Weakness: CWE-674 (Uncontrolled Recursion)

## Which versions are affected by CVE-2024-1899?

2 open source packages ship an affected version, including showdown. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `showdown` | npm | All versions to 2.1.0 | None |
| `showdown` | npm | All versions to 2.1.0 | None |

Products: Showdownjs Showdown.

## How do I fix CVE-2024-1899?

Upgrade to a fixed version.

## Is CVE-2024-1899 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2024-1899 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-1899 and fix it if it is affected.

What it is: CVE-2024-1899 is a medium-severity denial of service vulnerability in Showdownjs Showdown, published on 26 Feb 2024. 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-2024-1899 exists.

Affected packages and fixed versions:
- showdown (npm): affected all versions up to 2.1.0; no fix listed
- showdown (npm): affected all versions up to 2.1.0; no fix listed

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-2024-1899/ (Markdown: https://insights.sbomify.com/CVE-2024-1899/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-1899
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-1899
- OSV: https://osv.dev/vulnerability/CVE-2024-1899

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-1899/
Summaries are generated and may contain mistakes; the official description above is the record.