CVE-2026-50129 Mastodon: Persistent anonymous DoS via unhandled NoMethodError in MATH_TRANSFORMER
Attackers can cause a denial of service on Mastodon servers by submitting malformed math nodes that trigger unhandled exceptions.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-50129?
CVE-2026-50129 is a high-severity denial of service vulnerability in mastodon, published on 24 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.5.11, 4.4.18, and 4.3.24, a DoS can be triggered by (Uncaught Exception vulerability), due to missing exception handling in the math sanitizer. Malformed <math> nodes can result in a DoS of a whole server or targeted users services, depending on the type of action that includes the malformed nodes and the services interacting with it. This vulnerability is fixed in 4.5.11, 4.4.18, and 4.3.24.
Weakness: CWE-248
Which versions are affected by CVE-2026-50129?
1 open source package ship an affected version, including mastodon.
| Package | Affected | Fixed in |
|---|---|---|
mastodon Bitnami | All versions | 4.3.24, 4.4.18, 4.5.11 |
How do I fix CVE-2026-50129?
Upgrade mastodon to a fixed version for your release line: 4.3.24, 4.4.18 or 4.5.11.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-50129 being exploited?
There is no known exploitation of CVE-2026-50129 in the wild and no public exploit code.
Sources
Also known as BIT-mastodon-2026-50129, GHSA-qrgq-9fx2-vf2r.