CVE-2026-23961: medium-severity vulnerability in mastodon
Mastodon may allow a remote suspension bypass
Published
E-mail alert when it lands in KEV, gets a public PoC or its score goes up.
13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 5.3epss 0.4%
Mastodon is a free, open-source social network server based on ActivityPub. Mastodon allows server administrators to suspend remote users to prevent interactions. However, some logic errors allow already-known posts from such suspended users to appear in timelines if boosted. Furthermore, under certain circumstances, previously-unknown posts from suspended users can be processed. This issue allows old posts from suspended users to occasionally end up on timelines on all Mastodon versions. Additionally, on Mastodon versions from v4.5.0 to v4.5.4, v4.4.5 to v4.4.11, v4.3.13 to v4.3.17, and v4.2.26 to v4.2.29, remote suspended users can partially bypass the suspension to get new posts in. Mastodon versions v4.5.5, v4.4.12, v4.3.18 are patched.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Affected products
mastodon · mastodonRelated CVEs — mastodon
In the same product, most dangerous first.
CVE-2023-36460CRITICALMastodon vulnerable to arbitrary file creation through media attachmentsEPSS 40.1%CVE-2024-23832CRITICALMastodon Remote user impersonation and takeoverEPSS 2.5%CVE-2023-36461HIGHMastodon vulnerable to Denial of Service through slow HTTP responsesEPSS 1.3%CVE-2023-28853HIGHMastodon's blind LDAP injection in login allows the attacker to leak arbitrary attributes from LDAP databaseEPSS 1.3%CVE-2023-36459CRITICALMastodon vulnerable to Cross-site Scripting through oEmbed preview cardsEPSS 1.2%CVE-2026-72916MEDIUMMastodon: SSRF Protection Bypass via IPv4-compatible IPv6 AddressesEPSS 1.0%