{"id":"UBUNTU-CVE-2026-27624","details":"Coturn is a free open source implementation of TURN and STUN Server. Coturn is commonly configured to block loopback and internal ranges using \"denied-peer-ip\" and/or default loopback restrictions. CVE-2020-26262 addressed bypasses involving \"0.0.0.0\", \"[::1]\" and \"[::]\", but IPv4-mapped IPv6 is not covered. When sending a \"CreatePermission\" or \"ChannelBind\" request with the \"XOR-PEER-ADDRESS\" value of \"::ffff:127.0.0.1\", a successful response is received, even though \"127.0.0.0/8\" is blocked via \"denied-peer-ip\". The root cause is that, prior to the updated fix implemented in version 4.9.0, three functions in \"src/client/ns_turn_ioaddr.c\" do not check \"IN6_IS_ADDR_V4MAPPED\". \"ioa_addr_is_loopback()\" checks \"127.x.x.x\" (AF_INET) and \"::1\" (AF_INET6), but not \"::ffff:127.0.0.1.\" \"ioa_addr_is_zero()\" checks \"0.0.0.0\" and \"::\", but not \"::ffff:0.0.0.0.\" \"addr_less_eq()\" used by \"ioa_addr_in_range()\" for \"denied-peer-ip\" matching: when the range is AF_INET and the peer is AF_INET6, the comparison returns 0 without extracting the embedded IPv4. Version 4.9.0 contains an updated fix to address the bypass of the fix for CVE-2020-26262.","modified":"2026-05-20T16:24:51.967110355Z","published":"2026-02-25T05:17:00Z","upstream":["CVE-2026-27624"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-27624"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-27624"},{"type":"REPORT","url":"https://github.com/coturn/coturn/security/advisories/GHSA-j8mm-mpf8-gvjg"},{"type":"REPORT","url":"https://github.com/coturn/coturn/commit/b80eb898ba26552600770162c26a8ae7f3661b0b"},{"type":"REPORT","url":"https://github.com/coturn/coturn/commit/b80eb898ba26552600770162c26a8ae7f3661b0b"},{"type":"REPORT","url":"https://github.com/coturn/coturn/security/advisories/GHSA-6g6j-r9rf-cm7p"}],"affected":[{"package":{"name":"coturn","ecosystem":"Ubuntu:16.04:LTS","purl":"pkg:deb/ubuntu/coturn?arch=source&distro=xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.4.5.4-2","4.5.0.2-3","4.5.0.3-1","4.5.0.3-1build1","4.5.0.3-1ubuntu0.2","4.5.0.3-1ubuntu0.3","4.5.0.3-1ubuntu0.4"],"ecosystem_specific":{"binaries":[{"binary_name":"coturn","binary_version":"4.5.0.3-1ubuntu0.4"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-27624.json"}},{"package":{"name":"coturn","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/coturn?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.5.0.6-1ubuntu2","4.5.0.7-1ubuntu1","4.5.0.7-1ubuntu2","4.5.0.7-1ubuntu2.18.04.1","4.5.0.7-1ubuntu2.18.04.2","4.5.0.7-1ubuntu2.18.04.3"],"ecosystem_specific":{"binaries":[{"binary_name":"coturn","binary_version":"4.5.0.7-1ubuntu2.18.04.3"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-27624.json"}},{"package":{"name":"coturn","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/coturn?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.5.1.1-1.1build1","4.5.1.1-1.1build2","4.5.1.1-1.1ubuntu0.20.04.1","4.5.1.1-1.1ubuntu0.20.04.2"],"ecosystem_specific":{"binaries":[{"binary_version":"4.5.1.1-1.1ubuntu0.20.04.2","binary_name":"coturn"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-27624.json"}},{"package":{"name":"coturn","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/coturn?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.5.2-3","4.5.2-3.1~ubuntu22.04.1"],"ecosystem_specific":{"binaries":[{"binary_name":"coturn","binary_version":"4.5.2-3.1~ubuntu22.04.1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-27624.json"}},{"package":{"name":"coturn","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/coturn?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.6.1-1build1","4.6.1-1build2","4.6.1-1build3","4.6.1-1build4"],"ecosystem_specific":{"binaries":[{"binary_name":"coturn","binary_version":"4.6.1-1build4"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-27624.json"}},{"package":{"name":"coturn","ecosystem":"Ubuntu:25.10","purl":"pkg:deb/ubuntu/coturn?arch=source&distro=questing"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.6.1-2build1"],"ecosystem_specific":{"binaries":[{"binary_name":"coturn","binary_version":"4.6.1-2build1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-27624.json"}},{"package":{"name":"coturn","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/coturn?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.6.1-2build1","4.6.1-2build2"],"ecosystem_specific":{"binaries":[{"binary_name":"coturn","binary_version":"4.6.1-2build2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-27624.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N"},{"type":"Ubuntu","score":"medium"}]}