What is CVE-2023-36461?

CVE-2023-36461 is a high-severity vulnerability in Joinmastodon Mastodon, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 7.5/10. Published 2023-07-06.

How severe is CVE-2023-36461?

High severity. CVSS v3 base score is 7.5 out of 10.

Is CVE-2023-36461 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Resource exhaustion in Joinmastodon Mastodon

CVE-2023-36461

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 duration of time, leading to the server becoming unresponsive. Versions 3.5.9, 4.0.5, and 4.1.3 contain a patch for this issue.

Published 2023-07-06 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.013 (70.2th percentile), scored 2026-10-20.

Low probability of exploitation in the next 30 days, but still tracked. 70th percentile — 70.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.013 · newest: 0.013 · change: 0.000

Affected products

Joinmastodon Mastodon
Mastodon — versions < 3.5.9, >= 4.0.0, < 4.0.5, >= 4.1.0, < 4.1.3

Weakness classification (CWE)

CWE-770 — Allocation of Resources Without Limits or Throttling

Public proof-of-concept exploits

fkie-cad/nvd-json-data-feeds

References

github.com/mastodon/mastodon/security/advisories/GHSA-9pxv-6qvf-pjwc (Third Party Advisory)
github.com/mastodon/mastodon/commit/c5929798bf7e56cc2c79b15bed0c4692ded3dcb6 (Patch, Third Party Advisory)
github.com/mastodon/mastodon/releases/tag/v3.5.9 (Third Party Advisory)
github.com/mastodon/mastodon/releases/tag/v4.0.5 (Third Party Advisory)
github.com/mastodon/mastodon/releases/tag/v4.1.3 (Third Party Advisory)
www.openwall.com/lists/oss-security/2023/07/06/7 (Mailing List)

Frequently asked questions

What is CVE-2023-36461?: CVE-2023-36461 is a high-severity vulnerability in Joinmastodon Mastodon, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 7.5/10. Published 2023-07-06.
How severe is CVE-2023-36461?: High severity. CVSS v3 base score is 7.5 out of 10.
Is CVE-2023-36461 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.