CVE-2026-23963: medium-severity vulnerability in mastodon
Mastodon missing length limits on list names, filter names, and filter keywords
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 4.3epss 0.4%
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:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
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%