Improper Certificate Validation in Mastodon - CVE-2026-59825
Published: July 28, 2026
Vulnerability identifier: #VU139920
CSH Severity: Medium
CVSS v4: 9.1 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-59825
CWE-ID: CWE-295
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to disclose sensitive information and tamper with data in transit.
The vulnerability exists due to improper certificate validation in SSL/TLS certificate verification for web process outbound requests when LDAP authentication is configured with certificate verification disabled. A remote attacker can present a forged or untrusted certificate to disclose sensitive information and tamper with data in transit.
Only instances using LDAP authentication with the environment variable LDAP_TLS_NO_VERIFY set to true are vulnerable, and only requests made from web processes are affected.
Affected software
Mastodon
How to mitigate CVE-2026-59825
Install security update from vendor's website.
Mastodon - addressed in versions 4.4.19, 4.5.12