CVE-2026-59825 Mastodon: Unwanted deactivation of SSL/TLS certificate verification
Attackers can bypass SSL/TLS certificate verification in Mastodon when LDAP authentication is configured with verification disabled, potentially enabling man-in-the-middle attacks.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-59825?
CVE-2026-59825 is a high-severity vulnerability in mastodon, published on 18 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.4.19 and from 4.5.0 until 4.5.12, Mastodon's app/models/concerns/user/ldap_authenticable.rb mutates OpenSSL::SSL::SSLContext::DEFAULT_PARAMS when LDAP authentication uses LDAP_TLS_NO_VERIFY=true, disabling SSL and TLS certificate verification globally for requests made by puma web processes while sidekiq background jobs remain unaffected. This issue is fixed in versions 4.4.19 and 4.5.12.
Weakness: CWE-295
Which versions are affected by CVE-2026-59825?
1 open source package ship an affected version, including mastodon.
| Package | Affected | Fixed in |
|---|---|---|
mastodon Bitnami | All versions | 4.4.19, 4.5.12 |
How do I fix CVE-2026-59825?
Upgrade mastodon to a fixed version for your release line: 4.4.19 or 4.5.12.
Is CVE-2026-59825 being exploited?
There is no known exploitation of CVE-2026-59825 in the wild and no public exploit code.
Sources
Also known as BIT-mastodon-2026-59825, GHSA-3rhr-8phh-jm86.