CVE-2025-62605: mastodon — Fix

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.

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CVSS v3.1 Score

4.3

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

Weakness Type (CWE)

CWE-754 CWE-754

Affected Products

Vendor	Product	Versions
joinmastodon	mastodon	4.4.0 — 4.4.8
joinmastodon	mastodon	All

References

Advisories & Patches

https://github.com/mastodon/mastodon/commit/2dc4552229b55e2e4adaef675e68ed7ae123d78e https://github.com/mastodon/mastodon/commit/405a49df44033e7d179f3d44d59fb68a67d54789 https://github.com/mastodon/mastodon/security/advisories/GHSA-8h43-rcqj-wpc6

Other References

https://github.com/mastodon/mastodon/releases/tag/v4.4.8 https://github.com/mastodon/mastodon/releases/tag/v4.5.0-beta.2

Frequently Asked Questions

What is CVE-2025-62605? +

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. It has a CVSS v3.1 base score of 4.3 (MEDIUM).

How severe is CVE-2025-62605? +

CVE-2025-62605 has a CVSS v3.1 score of 4.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2025-62605? +

CVE-2025-62605 affects products from joinmastodon, specifically: mastodon. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-62605? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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