CVE-2026-23961

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{}

{"analysis": {"en": {"generated_at": "2026-04-18T03:59:51.666584+00:00", "value": {"mitigation_remediation": ["Upgrade Mastodon to the latest patched release (v4.5.5, v4.4.12, or v4.3.18 depending on the major version) to apply the vendor fix.", "Review and adjust moderation settings to ensure that suspended users cannot have their posts boosted or displayed in other users\u2019 timelines, thereby reinforcing the missing authorization check.", "Regularly monitor the Mastodon security advisory page for new patches and validate that no new posts from suspended users appear in public timelines as a sanity check."], "summary": {"action": "Patch", "impact": "Suspension bypass allowing content from suspended users to appear"}, "threat_synthesis": {"affected_systems": "All Mastodon instances are vulnerable. Unpatched versions include the full distribution as well as the ranges v4.5.0 through v4.5.4, v4.4.5 through v4.4.11, v4.3.13 through v4.3.17, and v4.2.26 through v4.2.29. Versions v4.5.5, v4.4.12, and v4.3.18 contain the vendor\u2011issued fix and are not affected.", "description_and_impact": "Mastodon allows administrators to suspend remote users so that their content normally disappears from timelines. A logic error in the enforcement of suspension status lets previously known posts reappear when boosted, and in specific release ranges also lets new posts from the suspended user be displayed to all users. This missing\u2011authorization flaw, identified as CWE\u2011863, undermines the administrative suspension, potentially exposing sensitive content or misleading audiences.", "risk_and_exploitability": "The CVSS score of 5.3 indicates a moderate severity, while the EPSS probability is below 1% and the vulnerability is not included in CISA\u2019s KEV catalog, suggesting a low but non\u2011zero exploitation risk. Attackers could exploit the flaw remotely via normal user actions such as boosting a suspended user\u2019s post or interacting with the public timeline API, with no elevated privileges required."}}}}, "created": "2026-01-22T10:07:59.033039+00:00", "updated": "2026-04-18T04:00:08.426745+00:00", "vendors": ["joinmastodon", "joinmastodon$PRODUCT$mastodon"]}