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.
Fix
Patch, vendor advisory and mitigation references on NVD 2
- https://github.com/mastodon/mastodon/pull/37077/commits/9957d3218cb33fea6a44bb285e2ba4795a059e4f Patch
- https://github.com/mastodon/mastodon/security/advisories/GHSA-gwhw-gcjx-72v8 Vendor Advisory
Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.
Change history 1
- First seenCVSS 3.7 · joinmastodonNVD modified 2026-10-14 21:10
Affected (CPE criteria) 1
cpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*