Vulnerability in Mastodon
CVE-2026-59825
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.
Vulnerability class: Improper Certificate Validation
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.4 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N.
EPSS exploit prediction
EPSS: 0.004 (28.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 29th percentile — 28.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.004 · change: +0.000
Affected products
- Mastodon — versions < 4.4.19, >= 4.5.0, < 4.5.12
Weakness classification (CWE)
References
- github.com/mastodon/mastodon/commit/2ccb6ef277e725d1932295690cf8ab9d3dc03149
- github.com/mastodon/mastodon/commit/5748d0b16ea09001e0933f76c7afe814e09652ef
- github.com/mastodon/mastodon/commit/761c61b42590a2fd91442fc15a0a7583e48bbea4
- github.com/mastodon/mastodon/pull/39571
- github.com/mastodon/mastodon/releases/tag/v4.4.19
- github.com/mastodon/mastodon/releases/tag/v4.5.12
- github.com/mastodon/mastodon/security/advisories/GHSA-3rhr-8phh-jm86
Frequently asked questions
- What is CVE-2026-59825?
- CVE-2026-59825 is a high-severity vulnerability in Mastodon, classified under Improper Certificate Validation. CVSS score: 7.4/10. Published 2026-08-18.
- How severe is CVE-2026-59825?
- High severity. CVSS v3 base score is 7.4 out of 10.