CVE-2025-62605 Mastodon quotes control can be bypassed

What is CVE-2025-62605?

CVE-2025-62605 is a medium-severity vulnerability in mastodon, published on 21 Oct 2025. Any signed-in user can exploit it over the network, with no action from the victim.

Official 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.

Weakness: CWE-754

Which versions are affected by CVE-2025-62605?

1 open source package ship an affected version, including mastodon. It affects 1 product.

Products include Joinmastodon Mastodon.

How do I fix CVE-2025-62605?

Upgrade mastodon to 4.4.8 or later.

Is CVE-2025-62605 being exploited?

There is no known exploitation of CVE-2025-62605 in the wild and no public exploit code.

Other vulnerabilities in mastodon

• CVE-2023-36460 Mastodon vulnerable to arbitrary file creation through media attachments Critical 10.0
• CVE-2022-2166 Improper Restriction of Excessive Authentication Attempts in mastodon/mastodon Critical 9.8
• CVE-2022-24307 Missing authorization in n/a Critical 9.8
• CVE-2018-21018 Auth bypass in n/a Critical 9.8
• CVE-2024-23832 Mastodon Remote user impersonation and takeover Critical 9.4

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BIT-mastodon-2025-62605, GHSA-8h43-rcqj-wpc6.