{"id":"CVE-2026-43994","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-43994","generatedAt":"2026-10-28T10:46:44.154Z","title":"Versions prior to 4.10.0 contain a stack buffer overflow in decode_oauth_token_gcm().","description":"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.","published":"2026-06-18T21:16:29.000Z","lastModified":"2026-06-26T02:30:38.000Z","status":"Analyzed","sourceIdentifier":"security-advisories@github.com","cvss":{"version":"3.1","score":9.8,"severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"},"cwe":["CWE-120"],"affected":["coturn project/coturn"],"epss":{"score":0.00675,"percentile":0.51971,"date":"2026-10-27","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.68%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://github.com/coturn/coturn/releases/tag/4.10.0","tags":["Release Notes"],"source":"security-advisories@github.com"},{"url":"https://github.com/coturn/coturn/security/advisories/GHSA-74pg-rfh2-5qw5","tags":["Exploit","Mitigation","Vendor Advisory"],"source":"security-advisories@github.com"},{"url":"https://github.com/coturn/coturn/security/advisories/GHSA-74pg-rfh2-5qw5","tags":["Exploit","Mitigation","Vendor Advisory"],"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-43994","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}