Coturn: Stack buffer overflow in decode_oauth_token_gcm()

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Summary

CVECVE-2026-43994
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-18 21:16:28 UTC
Updated2026-06-22 19:16:54 UTC
DescriptionCoturn 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.

Risk And Classification

Primary CVSS: v3.1 8.1 HIGH from [email protected]

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Problem Types: CWE-120 | CWE-120 CWE-120: Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary8.1HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED8.1HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Coturn Coturn affected < 4.10.0 Not specified

References

ReferenceSourceLinkTags
github.com/coturn/coturn/releases/tag/4.10.0 [email protected] github.com
github.com/coturn/coturn/security/advisories/GHSA-74pg-rfh2-5qw5 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
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