Vulnerability Details CVE-2026-43994
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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.004
EPSS Ranking 35.9%
CVSS Severity
CVSS v3 Score 8.1
Products affected by CVE-2026-43994
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cpe:2.3:a:coturn_project:coturn:4.4.5.3
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cpe:2.3:a:coturn_project:coturn:4.4.5.4
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cpe:2.3:a:coturn_project:coturn:4.5.0.1
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cpe:2.3:a:coturn_project:coturn:4.5.0.2
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cpe:2.3:a:coturn_project:coturn:4.5.0.3
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cpe:2.3:a:coturn_project:coturn:4.5.0.4
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cpe:2.3:a:coturn_project:coturn:4.5.0.5
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cpe:2.3:a:coturn_project:coturn:4.5.0.6
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cpe:2.3:a:coturn_project:coturn:4.5.0.7
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cpe:2.3:a:coturn_project:coturn:4.5.0.8
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cpe:2.3:a:coturn_project:coturn:4.5.0.9
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cpe:2.3:a:coturn_project:coturn:4.5.1.0
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cpe:2.3:a:coturn_project:coturn:4.5.1.1
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cpe:2.3:a:coturn_project:coturn:4.5.1.2
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cpe:2.3:a:coturn_project:coturn:4.5.1.3
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cpe:2.3:a:coturn_project:coturn:4.5.2
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cpe:2.3:a:coturn_project:coturn:4.6.0
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cpe:2.3:a:coturn_project:coturn:4.6.1
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cpe:2.3:a:coturn_project:coturn:4.6.2
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cpe:2.3:a:coturn_project:coturn:4.6.3
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cpe:2.3:a:coturn_project:coturn:4.7.0
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cpe:2.3:a:coturn_project:coturn:4.8.0
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cpe:2.3:a:coturn_project:coturn:4.9.0