CVE-2026-43994
Coturn: 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.
INFO
Published Date :
June 18, 2026, 9:16 p.m.
Last Modified :
June 26, 2026, 2:30 a.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 3.1 | CRITICAL | [email protected] |
Solution
- Update Coturn to version 4.10.0 or newer.
- Review and apply security patches promptly.
- Ensure OAuth mode is configured securely.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-43994.
| URL | Resource |
|---|---|
| https://github.com/coturn/coturn/releases/tag/4.10.0 | Release Notes |
| https://github.com/coturn/coturn/security/advisories/GHSA-74pg-rfh2-5qw5 | Exploit Mitigation Vendor Advisory |
| https://github.com/coturn/coturn/security/advisories/GHSA-74pg-rfh2-5qw5 | Exploit Mitigation Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-43994 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-43994
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-43994 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-43994 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Jun. 26, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Added CPE Configuration OR *cpe:2.3:a:coturn_project:coturn:*:*:*:*:*:*:*:* versions up to (excluding) 4.10.0 Added Reference Type GitHub, Inc.: https://github.com/coturn/coturn/releases/tag/4.10.0 Types: Release Notes Added Reference Type GitHub, Inc.: https://github.com/coturn/coturn/security/advisories/GHSA-74pg-rfh2-5qw5 Types: Exploit, Mitigation, Vendor Advisory Added Reference Type CISA-ADP: https://github.com/coturn/coturn/security/advisories/GHSA-74pg-rfh2-5qw5 Types: Exploit, Mitigation, Vendor Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 22, 2026
Action Type Old Value New Value Added Reference https://github.com/coturn/coturn/security/advisories/GHSA-74pg-rfh2-5qw5 Added SSVC {'id': 'CVE-2026-43994', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'poc'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-06-22T18:06:24.207624Z'} -
New CVE Received by [email protected]
Jun. 18, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'coturn', 'product': 'coturn', 'versions': [{'status': 'affected', 'version': '< 4.10.0'}]}] Added 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. Added CVSS V3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H Added CWE CWE-120 Added Reference https://github.com/coturn/coturn/releases/tag/4.10.0 Added Reference https://github.com/coturn/coturn/security/advisories/GHSA-74pg-rfh2-5qw5