What’s Vulnerable › Vulnerabilities

CVE-2025-62605: Mastodon quotes control can be bypassed

• Severity: medium (CVSS 4.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-10-21 · updated 2026-10-19
• Weakness: CWE-754

Description

Mastodon is a free, open-source social network server based on ActivityPub. In Mastodon version 4.4, support for verifiable quote posts with quote controls was added, but it is possible for an attacker to bypass these controls in Mastodon versions prior to 4.4.8 and 4.5.0-beta.2. Mastodon internally treats reblogs as statuses. Since they were not special-treated, an attacker could reblog any post, then quote their reblog, technically quoting themselves, but having the quote feature a preview of the post they did not get authorization for with all of the affordances that would be otherwise denied by the quote controls. This issue has been patched in versions 4.4.8 and 4.5.0-beta.2.

Affected products

• mastodon: from 4.4.0 before 4.4.8; 4.5.0-beta1 — fixed in 4.4.8

How to fix

Upgrade to a fixed version: mastodon 4.4.8. Check the vendor advisory for mitigations.

References

• https://github.com/mastodon/mastodon/commit/2dc4552229b55e2e4adaef675e68ed7ae123d78e
• https://github.com/mastodon/mastodon/commit/405a49df44033e7d179f3d44d59fb68a67d54789
• https://github.com/mastodon/mastodon/releases/tag/v4.4.8
• https://github.com/mastodon/mastodon/releases/tag/v4.5.0-beta.2
• https://github.com/mastodon/mastodon/security/advisories/GHSA-8h43-rcqj-wpc6

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