Cyber Resilience

CVE-2026-43994

HighPublic PoCUpdated

Published: 18 June 2026

Published
18 June 2026
Modified
26 June 2026
KEV Added
—
Patch
—
CVSS Score v3.1 8.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.0045 36.0th percentile
Risk Priority 55 floored blend · peak EPSS

Summary

CVE-2026-43994 is a high-severity Classic Buffer Overflow (CWE-120) vulnerability in Coturn Project Coturn. Its CVSS base score is 8.1 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 36.0th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

EU & UK References

Vulnerability 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()…

more

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.

CWE(s)
CWE-120

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
Why these techniques?

Stack buffer overflow in public-facing Coturn TURN/STUN server (OAuth token handler) directly enables remote exploitation for RCE.

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

Affected Assets

coturn project
coturn
≤ 4.10.0

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

SC-27 Platform-independent Applications
addresses: CWE-120

Platform-independent managed code eliminates the need for unchecked native buffer copies that are the root cause of classic buffer overflows.

References