Input validation error in Mastodon - #VU126980
Published: February 27, 2025 / Updated: April 23, 2026
Vulnerability identifier: #VU126980
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: N/A
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Mastodon
Affected software:
Mastodon
Mastodon
Detailed vulnerability description
The vulnerability allows a remote attacker to conduct phishing attacks through top-level navigation.
The vulnerability exists due to improper input validation in the OEmbed HTML sanitization configuration when processing OEmbed embeds. A remote attacker can supply a crafted OEmbed containing an embed tag to conduct phishing attacks through top-level navigation.
Exploitation is only possible if the deployment environment is severely misconfigured.
Remediation
Install security update from vendor's website.