Coturn: Pre-authentication heap memory disclosure in ACME redirect (`try_acme_redirect`)
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- Present
- Impact type
- Information disclosure
- Confidentiality · integrity · availability
- High · None · None
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-125 and the CVSS impact.
Summary
Coturn is a free open source implementation of TURN and STUN Server. From 4.5.2 through 4.14.0, when Coturn is started with --acme-redirect <URL> and exposes a plaintext-TCP listener, an unauthenticated remote client can send a single ordinary HTTP GET request and receive a 301 response whose Location header contains up to ~870 bytes of adjacent process heap memory. The leaked region is a recycled network receive buffer that is reused without being zeroed, so on a busy server it can contain data from other clients' requests (TURN credentials, OAuth tokens, relayed payloads). Root cause is a signed→unsigned conversion. This issue is fixed in version 4.15.0.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
- Fix · CNA coturn (coturn) Fixed in 4.15.0
Vendor assessments
Timeline
- 2026-10-02 Threatist record created from CVE-2026-62959
References
More coturn vulnerabilities
- TI-2026-32037 Coturn: Stack buffer overflow in decode_oauth_token_gcm() CVSS 3.1CRITICAL 9.8
- TI-2026-29348 Coturn: Misaligned Memory Access in coturn STUN Attribute Parser (Remote DoS on ARM64) CVSS 3.1HIGH 7.5
- TI-2026-22006 Coturn: IPv4-mapped IPv6 (::ffff:0:0/96) bypasses denied-peer-ip ACL CVSS 3.1HIGH 7.2
- TI-2026-38529 Coturn: SQL Injection in HTTPS Admin Panel Delete Operations CVSS 3.1HIGH 7.2
- TI-2026-46994 Coturn: MOBILITY-TICKET session-resume authorization bypass allows cross-user TURN allocation takeover CVSS 3.1HIGH 7.1
- TI-2026-38531 Coturn: IPv4-mapped 127.0.0.1 bypasses default loopback peer protection CVSS 3.1HIGH 7.4
Sources
- CVE-2026-62959 · CVE Program
- CVE-2026-62959 · NVD
- FIRST EPSS
- CVE-2026-62959 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences