CVE-2026-47389

The record

Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.5.10, 4.4.17, and 4.3.23, when using Ruby versions older than 3.4, PrivateAddressCheck.private_address? returns false for IPv4-mapped IPv6 addresses (::ffff:a.b.c.d) corresponding to some private IPv4 addresses, depending on Ruby version, this can include loopback, RFC1918 private networks, and link-local space. An attacker who controls DNS for any domain can publish an AAAA record with such a mapped address; any outbound HTTP fetch Mastodon performs against that hostname then opens a real TCP connection to the underlying IPv4 address, including 127.0.0.1 and cloud-metadata endpoints such as 169.254.169.254. This vulnerability is fixed in 4.5.10, 4.4.17, and 4.3.23.

Affected packages

Related vulnerabilities

• CVE-2026-114729 Roundcube Webmail before 1.6.20 and 1.7.x before 1.7.5 is affected by a remote content… CWE-184
• CVE-2026-114728 Roundcube Webmail before 1.6.20 and 1.7.x before 1.7.5 is affected by a remote content… CWE-184
• CVE-2026-106445 Handlebars provides the power necessary to let users build semantic templates. CWE-184
• CVE-2026-102828 simple-git, an interface for running git commands in any node.js application, enables… CWE-184
• CVE-2026-102829 simple-git, an interface for running git commands in any node.js application, enables… CWE-184
• CVE-2026-87985 An arbitrary code execution vulnerability in Mistral Vibe allows an attacker to bypass… CWE-184
• CVE-2026-87911 An OS command injection weakness in the read-only enforcement of the SQL validation… CWE-184
• CVE-2026-85788 Incomplete list of disallowed inputs in the mutable SQL detector component in Amazon… CWE-184