# CVE-2026-50129: Mastodon denial of service via uncaught exception in math sanitizer

Source: https://junglewise.ai/threats/cve-2026-50129-mastodon-denial-of-service-via-uncaught-exception-in-math  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-24. Updated: 2026-06-24  
License: CC BY 4.0 with a link back

CVE-2026-50129 · Severity: high · CVSS 7.5 · Published 2026-06-24

Mastodon is an open-source social networking platform. A vulnerability in how the server processes mathematical formulas allows an attacker to crash the service by sending specially crafted content. This can result in a total service outage for the entire server or targeted disruptions for specific users and their followers.

Technologies: [Mastodon](https://junglewise.ai/threats/technologies/mastodon). Vendors: [Mastodon](https://junglewise.ai/threats/vendors/mastodon).

## Quick answers

**Is CVE-2026-50129 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-50129 being exploited in the wild.

**How severe is CVE-2026-50129?** High severity, with a CVSS score of 7.5, published 24 June 2026.

**Which products and versions are affected?** Mastodon < 4.3.24, 4.4.0-beta.1 to < 4.4.18, 4.5.0-beta.1 to < 4.5.11.

**Is there a fix for CVE-2026-50129?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-50129 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-50129?** Check whether you run Mastodon at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A Denial of Service (DoS) vulnerability exists in Mastodon due to an uncaught 'NoMethodError' exception within the 'MATH_TRANSFORMER' component. The root cause is missing exception handling in the math sanitizer when processing malformed <math> nodes. An unauthenticated remote attacker can exploit this by posting or sending forged content containing these nodes. Depending on where the content is viewed, this can crash the rendering of timelines, RSS feeds, or specific user profiles, effectively disabling access to those services. The issue is resolved in versions 4.5.11, 4.4.18, and 4.3.24.

## Affected products

- Mastodon Mastodon < 4.3.24, 4.4.0-beta.1 to < 4.4.18, 4.5.0-beta.1 to < 4.5.11

## Timeline

- 2026-06-03: advisory: GitHub security advisory published
- 2026-06-24: disclosed: CVE published to NVD

## References

- [https://github.com/mastodon/mastodon/security/advisories/GHSA-qrgq-9fx2-vf2r](https://github.com/mastodon/mastodon/security/advisories/GHSA-qrgq-9fx2-vf2r)

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