CVE-2026-43994
Versions prior to 4.10.0 contain a stack buffer overflow in decode_oauth_token_gcm().
Does this matter?
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.
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.
- CVSS 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 0.68% probability · 50th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-120
- Affected
- coturn project/coturn
- Source
- security-advisories@github.com
References
- https://github.com/coturn/coturn/releases/tag/4.10.0Release Notes
- https://github.com/coturn/coturn/security/advisories/GHSA-74pg-rfh2-5qw5Exploit, Mitigation, Vendor Advisory
- https://github.com/coturn/coturn/security/advisories/GHSA-74pg-rfh2-5qw5Exploit, Mitigation, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.