What’s Vulnerable › Vulnerabilities

CVE-2023-28853: Mastodon's blind LDAP injection in login allows the attacker to leak arbitrary attributes from LDAP database

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.3% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2023-04-04 · updated 2026-06-17
• Weakness: CWE-90

Description

Mastodon is a free, open-source social network server based on ActivityPub Mastodon allows configuration of LDAP for authentication. Starting in version 2.5.0 and prior to versions 3.5.8, 4.0.4, and 4.1.2, the LDAP query made during login is insecure and the attacker can perform LDAP injection attack to leak arbitrary attributes from LDAP database. This issue is fixed in versions 3.5.8, 4.0.4, and 4.1.2.

Affected products

• mastodon: from 2.5.0 before 3.5.8; from 4.0.0 before 4.0.4; from 4.1.0 before 4.1.2 — fixed in 3.5.8, 4.0.4, 4.1.2

How to fix

Upgrade to a fixed version: mastodon 3.5.8, 4.0.4, 4.1.2. Check the vendor advisory for mitigations.

References

• http://www.openwall.com/lists/oss-security/2023/07/06/6
• https://github.com/mastodon/mastodon/blob/94cbd808b5b3e7999c7e77dc724b7e8c9dd2bdec/app/models/concerns/ldap_authenticable.rb#L7-L14
• https://github.com/mastodon/mastodon/blob/94cbd808b5b3e7999c7e77dc724b7e8c9dd2bdec/config/initializers/devise.rb#L398-L414
• https://github.com/mastodon/mastodon/pull/24379
• https://github.com/mastodon/mastodon/releases/tag/v3.5.8
• https://github.com/mastodon/mastodon/releases/tag/v4.0.4
• https://github.com/mastodon/mastodon/releases/tag/v4.1.2
• https://github.com/mastodon/mastodon/security/advisories/GHSA-38g9-pfm9-gfqv
• http://www.openwall.com/lists/oss-security/2023/07/06/6
• https://github.com/mastodon/mastodon/blob/94cbd808b5b3e7999c7e77dc724b7e8c9dd2bdec/app/models/concerns/ldap_authenticable.rb#L7-L14
• https://github.com/mastodon/mastodon/blob/94cbd808b5b3e7999c7e77dc724b7e8c9dd2bdec/config/initializers/devise.rb#L398-L414
• https://github.com/mastodon/mastodon/pull/24379

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