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Vulnerability record · CVE-2026-59825 · published 18 August 2026

CVE-2026-59825: Improper certificate validation vulnerability

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.

7.4 CVSS 3.1 High EPSS 0.37% · top 71.4% CWE-295 · Improper certificate validation Deferred
7.4CVSS 3.1 base score
0.37%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
7References
16 Sep 2026Last modified by NVD

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.

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

References

LinkTags
https://github.com/mastodon/mastodon/commit/2ccb6ef277e725d1932295690cf8ab9d3dc03149
https://github.com/mastodon/mastodon/commit/5748d0b16ea09001e0933f76c7afe814e09652ef
https://github.com/mastodon/mastodon/commit/761c61b42590a2fd91442fc15a0a7583e48bbea4
https://github.com/mastodon/mastodon/pull/39571
https://github.com/mastodon/mastodon/releases/tag/v4.4.19
https://github.com/mastodon/mastodon/releases/tag/v4.5.12
https://github.com/mastodon/mastodon/security/advisories/GHSA-3rhr-8phh-jm86

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Source: NIST National Vulnerability Database (record CVE-2026-59825), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.