CVE-2023-36461 — Mastodon is a free, open-source social network server based on ActivityPub

Mastodon is a free, open-source social network server based on ActivityPub. When performing outgoing HTTP queries, Mastodon sets a timeout on individual read operations. Prior to versions 3.5.9, 4.0.5, and 4.1.3, a malicious server can indefinitely extend the duration of the resp

01What is this vulnerability?

Mastodon is a free, open-source social network server based on ActivityPub. When performing outgoing HTTP queries, Mastodon sets a timeout on individual read operations. Prior to versions 3.5.9, 4.0.5, and 4.1.3, a malicious server can indefinitely extend the duration of the response through slowloris-type attacks. This vulnerability can be used to keep all Mastodon workers busy for an extended…

02Affected products

Vendor	Product	Versions
mastodon	mastodon	< 3.5.9, >= 4.0.0, < 4.0.5, >= 4.1.0, < 4.1.3

03Active exploitation status

Not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. EPSS is the best forward-looking signal — see the EPSS row above.

04Recommended remediation

• Patch to a fixed version listed in the vendor advisory (see references below).
• Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
• Hunt historical logs for exploitation indicators — see Detection signatures below.

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Ask SARA in chat to draft a starting detection for this CVE in your stack of choice.

07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

• Published: 2023-07-06T18:57:59.160Z
• Last modified: 2025-02-13T16:56:18.466Z

09References

• github.com — https://github.com/mastodon/mastodon/security/advisories/GHSA-9pxv-6qvf-pjwc
• github.com — https://github.com/mastodon/mastodon/commit/c5929798bf7e56cc2c79b15bed0c4692ded3…
• github.com — https://github.com/mastodon/mastodon/releases/tag/v3.5.9
• github.com — https://github.com/mastodon/mastodon/releases/tag/v4.0.5
• github.com — https://github.com/mastodon/mastodon/releases/tag/v4.1.3
• www.openwall.com — http://www.openwall.com/lists/oss-security/2023/07/06/7