CVE-2025-67500 Mastodon Error Handling Discrepancy Enables Private Status Existence Enumeration

What is CVE-2025-67500?

CVE-2025-67500 is a low-severity vulnerability in mastodon, published on 9 Dec 2025. 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. Versions 4.2.27 and prior, 4.3.0-beta.1 through 4.3.14, 4.4.0-beta.1 through 4.4.9, 4.5.0-beta.1 through 4.5.2 have discrepancies in error handling which allow checking whether a given status exists by sending a request with a non-English Accept-Language header. Using this behavior, an attacker who knows the identifier of a particular status they are not allowed to see can confirm whether this status exists or not. This cannot be used to learn the contents of the status or any other property besides its existence. This issue is fixed in versions 4.2.28, 4.3.15, 4.4.10 and 4.5.3.

Weakness: CWE-204

Which versions are affected by CVE-2025-67500?

1 open source package ship an affected version, including mastodon. It affects 1 product.

Products include Joinmastodon Mastodon.

How do I fix CVE-2025-67500?

Upgrade mastodon to a fixed version for your release line: 4.2.28, 4.3.15, 4.4.10 or 4.5.3.

Is CVE-2025-67500 being exploited?

There is no known exploitation of CVE-2025-67500 in the wild and no public exploit code.

Other vulnerabilities in mastodon

• CVE-2023-36460 Mastodon vulnerable to arbitrary file creation through media attachments Critical 10.0
• CVE-2022-2166 Improper Restriction of Excessive Authentication Attempts in mastodon/mastodon Critical 9.8
• CVE-2022-24307 Missing authorization in n/a Critical 9.8
• CVE-2018-21018 Auth bypass in n/a Critical 9.8
• CVE-2024-23832 Mastodon Remote user impersonation and takeover Critical 9.4

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BIT-mastodon-2025-67500, GHSA-gwhw-gcjx-72v8.