CVE-2026-23963

MEDIUM EPSS 21.3%
Published Jan 22, 20265mo ago · Modified Jun 17, 20261w ago
6.5 CVSS 3.1
Medium
Find Similar
Published Jan 22, 2026 5mo ago
Last Modified Jun 17, 2026 1w ago

Description

Mastodon is a free, open-source social network server based on ActivityPub. Prior to versions 4.5.5, 4.4.12, and 4.3.18, the server does not enforce a maximum length for the names of lists or filters, or for filter keywords, allowing any user to set an arbitrarily long string as the name or keyword. Any local user can abuse the list or filter fields to cause disproportionate storage and computing resource usage. They can additionally cause their own web interface to be unusable, although they must intentionally do this to themselves or unknowingly approve a malicious API client. Mastodon versions v4.5.5, v4.4.12, v4.3.18 are patched.

CVSS Details

Base Score
6.5
Exploitability
2.8
Impact
3.6
Vector string
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack Vector Network
Attack Complexity Low
Privileges Required Low
User Interaction None
Scope Unchanged
Confidentiality None
Integrity None
Availability High

Threat Intelligence

EPSS Exploit Probability
21.3% percentile
Exploit & Patch Status
No Known Exploit
No Patch Available

Weaknesses 1

CWE-770

Affected Products 3

VendorProductVersionRange
joinmastodonmastodon* <4.3.18
joinmastodonmastodon*≥4.4.0  –  <4.4.12
joinmastodonmastodon*≥4.5.0  –  <4.5.5

References 4

  • github.com https://github.com/mastodon/mastodon/releases/tag/v4.3.18
    Release Notes
  • github.com https://github.com/mastodon/mastodon/releases/tag/v4.4.12
    Release Notes
  • github.com https://github.com/mastodon/mastodon/releases/tag/v4.5.5
    Release Notes
  • github.com https://github.com/mastodon/mastodon/security/advisories/GHSA-6x3w-9g92-gvf3
    Vendor Advisory

Remediation

No remediation data recorded yet

Check vendor advisories and the NVD entry for patch availability.