TI-2023-18303 Aliases CVE-2023-36462

Mastodon's verified profile links can be formatted in a misleading way

LOW 25CWE-20Published 2023-07-06 · Updated 2024-10-24

Key facts

Attack vector: Network
Privileges required: None
User interaction: Required
Attack complexity: Low
Impact type: —
Confidentiality · integrity · availability: Low · Low · None
Fix status: Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00622 50th percentileScored 2026-11-07

Fix Fixed mastodon (mastodon): 3.5.9, 4.0.5, 4.1.3

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
mastodon	mastodon	2.6.0 to before 3.5.9; 4.0.0 to before 4.0.5; 4.1.0 to before 4.1.3	3.5.9, 4.0.5, 4.1.3	Patch available	CNA

mastodon Vendormastodon Affected 2.6.0 to before 3.5.9; 4.0.0 to before 4.0.5; 4.1.0 to before 4.1.3 Fixed in 3.5.9, 4.0.5, 4.1.3 Patch available CNA

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:joinmastodon:mastodon::::::::	2.6.0 to before 3.5.9; 4.0.0 to before 4.0.5; 4.1.0 to before 4.1.3	Vulnerable	mastodon

cpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:* Versions 2.6.0 to before 3.5.9; 4.0.0 to before 4.0.5; 4.1.0 to before 4.1.3 Vulnerable ·mastodon

Remediation

Fix · CNA mastodon (mastodon) Fixed in 3.5.9, 4.0.5, 4.1.3

Timeline

2026-10-02 Threatist record created from CVE-2023-36462
2026-11-07 EPSS moved to the 50th–90th percentile

References

Patch 1

https://github.com/mastodon/mastodon/commit/610731b03dfcadd887078cb0399f4e514aa1931c

Advisory 1

https://github.com/mastodon/mastodon/security/advisories/GHSA-55j9-c3mp-6fcq

Other 3

TI-2022-02004 Improper Restriction of Excessive Authentication Attempts in mastodon/mastodon CVSS 3.1CRITICAL 9.8
TI-2025-34613 Mastodon e‑mail throttle misconfiguration allows unlimited email confirmations against unconfirmed emails CVSS 3.1HIGH 7.5
TI-2022-22936 Mastodon through 4.0.2 allows attackers to cause a denial of service (large Sidekiq pull… CVSS 3.1HIGH 7.5
TI-2023-18301 Mastodon vulnerable to arbitrary file creation through media attachments CVSS 3.1CRITICAL 10.0
TI-2023-13359 Mastodon's blind LDAP injection in login allows the attacker to leak arbitrary attributes from LDAP database CVSS 3.1HIGH 7.7
TI-2024-16846 External OpenID Connect Account Takeover by E-Mail Change in mastodon CVSS 3.1HIGH 7.4

See all 41 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences