{"id":"UBUNTU-CVE-2026-43994","details":"Coturn is a free open source implementation of TURN and STUN Server. Versions prior to 4.10.0 contain a stack buffer overflow in decode_oauth_token_gcm(). A uint16_t nonce_len field read from an attacker-supplied OAuth access token (0-65535) is passed directly to memcpy() as the copy length into a 256-byte stack buffer (oauth_encrypted_block.nonce[256]) without bounds checking. The overflow occurs before AES-GCM authentication is verified, the attacker does not need to know the OAuth key or produce a valid AES-GCM token. Up to 735 bytes of attacker-controlled data are written past the buffer, may corrupt adjacent stack data, including control-flow data depending on compiler, ABI, and mitigations. Requires --oauth mode (non-default). This may provide a plausible RCE primitive depending on exploit mitigations; because coturn is widely deployed for WebRTC TURN/STUN and --oauth is commonly recommended, impact can be broad. This issue has been fixed in version 4.10.0.","modified":"2026-06-29T13:50:24.255548781Z","published":"2026-06-18T21:16:00Z","upstream":["CVE-2026-43994"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-43994"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-43994"},{"type":"REPORT","url":"https://github.com/coturn/coturn/security/advisories/GHSA-74pg-rfh2-5qw5"},{"type":"REPORT","url":"https://github.com/coturn/coturn/commit/5ca467e70915c033f371cd7a9742759c68f56363"},{"type":"REPORT","url":"https://github.com/coturn/coturn/releases/tag/4.10.0"}],"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_version":"4.5.0.3-1ubuntu0.4","binary_name":"coturn"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-43994.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-2026-43994.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_name":"coturn","binary_version":"4.5.1.1-1.1ubuntu0.20.04.2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-43994.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-2026-43994.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-2026-43994.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-2026-43994.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_version":"4.6.1-2build2","binary_name":"coturn"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-43994.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"},{"type":"Ubuntu","score":"medium"}]}