High severity · published Aug 18, 2026
CVE-2026-59825
Mastodon: Unwanted deactivation of SSL/TLS certificate verification
7.4
CVSS
0.4%
EPSS
No
On KEV
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 vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 31% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
MA
mastodon · mastodon
< 4.4.19; >= 4.5.0, < 4.5.12 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-59825
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-59825
github.com
https://github.com/mastodon/mastodon/commit/2ccb6ef277e725d1932295690cf8ab9d3dc03149
github.com
https://github.com/mastodon/mastodon/commit/5748d0b16ea09001e0933f76c7afe814e09652ef
github.com
https://github.com/mastodon/mastodon/commit/761c61b42590a2fd91442fc15a0a7583e48bbea4
github.com
https://github.com/mastodon/mastodon/pull/39571
github.com
https://github.com/mastodon/mastodon/releases/tag/v4.4.19
github.com
https://github.com/mastodon/mastodon/releases/tag/v4.5.12
More from mastodon
8.7
CVE-2026-46348
Mastodon: SSRF Bypass via IPv6 Unspecified Address (::)
8.6
CVE-2026-47389
Mastodon: SSRF protection bypass on older Ruby versions
8.2
CVE-2026-27468
Mastodon may allow unconfirmed FASP to make subscriptions
7.5
CVE-2026-72915
Mastodon: Personally-identifying information disclosure due to incorrect access control validation
7.5
CVE-2026-72914
Mastodon: Exhausting data by an unauthenticated request to the admin retention API