CVE-2026-43994: Coturn is a free open source implementation of TURN and STUN Server

Q: How do I fix CVE-2026-43994?

coturn: upgrade to 4.10.0. Exact commands for each OS are on this page.

Q: Is CVE-2026-43994 being exploited?

CVE-2026-43994 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-43994 affect?

CVE-2026-43994 affects coturn. Severity is high (CVSS 8.1). 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

Q: How urgent is CVE-2026-43994?

Priority 51/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

This week

HIGH 8.1REMOTEUPGRADE

CVE-2026-43994 is a high-severity flaw (CVSS 8.1) affecting coturn. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 at

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	8.1 (High)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.7% (top 48%)
CISA exploited list	No
Weakness	CWE-120
Published	2026-06-18
Last modified	2026-06-26

Publisher (CNA): GitHub, Inc. · Vendor: coturn project

Last updated 2026-06-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-06-18 21:16 UTCPublished CVE record published
2026-06-26 02:30 UTCUpdated Record last modified

coturn project coturn UPGRADE

Affected: < 4.10.0

Fixed in: 4.10.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy coturn || rpm -q coturn || coturn --version

2. UPGRADE to 4.10.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade coturn

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade coturn

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-43994?

coturn: upgrade to 4.10.0. Exact commands for each OS are on this page.

Is CVE-2026-43994 being exploited?

CVE-2026-43994 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-43994 affect?

CVE-2026-43994 affects coturn. Severity is high (CVSS 8.1). 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

How urgent is CVE-2026-43994?

Priority 51/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-53450 HIGH 7.4 UPGRADE Coturn is a free open source implementation of TURN and STUN Server
CVE-2026-53448 HIGH 7.2 UPGRADE Coturn is a free open source implementation of TURN and STUN Server
CVE-2026-53449 MEDIUM 6.0 UPGRADE Coturn is a free open source implementation of TURN and STUN Server
CVE-2026-43915 MEDIUM 5.4 UPGRADE Coturn is a free open source implementation of TURN and STUN Server

References

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