What is CVE-2023-36462?

CVE-2023-36462 is a medium-severity vulnerability in Joinmastodon Mastodon, classified under Improper Input Validation. CVSS score: 5.4/10. Published 2023-07-06.

How severe is CVE-2023-36462?

Medium severity. CVSS v3 base score is 5.4 out of 10.

Is CVE-2023-36462 known to be exploited?

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

Improper input validation in Joinmastodon Mastodon

CVE-2023-36462

Mastodon is a free, open-source social network server based on ActivityPub. Starting in version 2.6.0 and prior to versions 3.5.9, 4.0.5, and 4.1.3, an attacker can craft a verified profile link using specific formatting to conceal arbitrary parts of the link, enabling it to appear to link to a different URL altogether. The link is visually misleading, but clicking on it will reveal the actual link. This can still be used for phishing, though, similar to IDN homograph attacks. Versions 3.5.9, 4.0.5, and 4.1.3 contain a patch for this issue.

Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)

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

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.006 (47.7th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 48th percentile — 47.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: 0.000

Affected products

Joinmastodon Mastodon
Mastodon — versions >= 2.6.0, < 3.5.9, >= 4.0.0, < 4.0.5, >= 4.1.0, < 4.1.3

Weakness classification (CWE)

CWE-20 — Improper Input Validation

Public proof-of-concept exploits

fkie-cad/nvd-json-data-feeds

References

github.com/mastodon/mastodon/security/advisories/GHSA-55j9-c3mp-6fcq (Vendor Advisory)
github.com/mastodon/mastodon/commit/610731b03dfcadd887078cb0399f4e514aa1931c (Patch)
github.com/mastodon/mastodon/releases/tag/v3.5.9 (Release Notes)
github.com/mastodon/mastodon/releases/tag/v4.0.5 (Release Notes)
github.com/mastodon/mastodon/releases/tag/v4.1.3 (Release Notes)

Frequently asked questions

What is CVE-2023-36462?: CVE-2023-36462 is a medium-severity vulnerability in Joinmastodon Mastodon, classified under Improper Input Validation. CVSS score: 5.4/10. Published 2023-07-06.
How severe is CVE-2023-36462?: Medium severity. CVSS v3 base score is 5.4 out of 10.
Is CVE-2023-36462 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.