{"cve":"CVE-2026-22246","nvd":{"published":"2026-01-08T16:16:02.957","modified":"2026-06-17T10:19:37.690","status":"Analyzed","description":"Mastodon is a free, open-source social network server based on ActivityPub. Mastodon 4.3 added notifications of severed relationships, allowing end-users to inspect the relationships they lost as the result of a moderation action. The code allowing users to download lists of severed relationships for a particular event fails to check the owner of the list before returning the lost relationships. Any registered local user can access the list of lost followers and followed users caused by any severance event, and go through all severance events this way. The leaked information does not include the name of the account which has lost follows and followers. This has been fixed in Mastodon v4.3.17, v4.4.11 and v4.5.4.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N","score":4.3},"cwes":["CWE-201"],"references":["https://github.com/mastodon/mastodon/commit/68e30985ca7afdb89af1b2e9dc962e1993dc8076","https://github.com/mastodon/mastodon/commit/b2bcd34486fd6681cc0f30028086ef0f47282adf","https://github.com/mastodon/mastodon/commit/c1fb6893c5175d74c074f6f786d504c8bc610d57","https://github.com/mastodon/mastodon/security/advisories/GHSA-ww85-x9cp-5v24"],"products":["joinmastodon:mastodon"],"source":"nvd","synced_at":"2026-10-19T22:19:41.481987139+00:00"},"epss":{"cve":"CVE-2026-22246","score":0.00268,"percentile":0.1894,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}