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CVE-2026-62959

Coturn: Pre-authentication heap memory disclosure in ACME redirect (`try_acme_redirect`)

8.2 HighFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
None
Availability
None

Exploit likelihood

0.52%Up 0.1 points since Aug 1, 2026
90%50%10%1%

What each source reports

CVE List Score used 8.2

Coturn: Pre-authentication heap memory disclosure in ACME redirect (`try_acme_redirect`)

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.

Record
CVE-2026-62959
CVSS 4.0
8.2 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
Weakness
CWE-125, CWE-195
Updated
2026-11-02
EUVDEUVD-2026-51627 8.2

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.

Record
EUVD-2026-51627
CVSS 4.0
8.2 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
Updated
2026-11-02
NVD 8.2

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.

Record
CVE-2026-62959
CVSS 4.0
8.2 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Weakness
CWE-125, CWE-195
Updated
2026-11-02
OSV 8.2

Coturn: Pre-authentication heap memory disclosure in ACME redirect (`try_acme_redirect`)

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.

Record
CVE-2026-62959
CVSS 4.0
8.2 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
Weakness
CWE-125, CWE-195
Updated
2026-11-02
OSVDEBIAN-CVE-2026-62959 8.2

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.

Record
DEBIAN-CVE-2026-62959
CVSS 4.0
8.2 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Updated
2026-11-02
OSVUBUNTU-CVE-2026-62959 8.2

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.

Record
UBUNTU-CVE-2026-62959
CVSS 4.0
8.2 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
Updated
2026-11-02
OSVopenSUSE-SU-2026:11617-1 No score

coturn-4.17.2-1.1 on GA media

These are all security issues fixed in the coturn-4.17.2-1.1 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2026:11617-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
coturn
Debian:12
All versions, plus listed versions
4.12.0-14.14.0-14.15.0-14.18.0-14.6.1-14.6.1-2
None known
coturn
Debian:13
All versions, plus listed versions
4.12.0-14.14.0-14.15.0-14.18.0-14.6.1-2
None known
coturn
Debian:14
before 4.15.0-1, plus listed versions
4.12.0-14.14.0-14.6.1-2
4.15.0-1
coturn
Ubuntu:16.04:LTS
All versions, plus listed versions
4.4.5.4-24.5.0.2-34.5.0.3-14.5.0.3-1build14.5.0.3-1ubuntu0.24.5.0.3-1ubuntu0.34.5.0.3-1ubuntu0.4
None known
coturn
Ubuntu:18.04:LTS
All versions, plus listed versions
4.5.0.6-1ubuntu24.5.0.7-1ubuntu14.5.0.7-1ubuntu24.5.0.7-1ubuntu2.18.04.14.5.0.7-1ubuntu2.18.04.24.5.0.7-1ubuntu2.18.04.3
None known
coturn
Ubuntu:20.04:LTS
All versions, plus listed versions
4.5.1.1-1.1build14.5.1.1-1.1build24.5.1.1-1.1ubuntu0.20.04.14.5.1.1-1.1ubuntu0.20.04.2
None known
coturn
Ubuntu:22.04:LTS
All versions, plus listed versions
4.5.2-34.5.2-3.1~ubuntu22.04.1
None known
coturn
Ubuntu:24.04:LTS
All versions, plus listed versions
4.6.1-1build14.6.1-1build24.6.1-1build34.6.1-1build4
None known
coturn
Ubuntu:26.10
All versions, plus listed versions
4.6.1-2build24.12.0-14.14.0-14.15.0-14.18.0-1
None known
coturn
Ubuntu:26.04:LTS
All versions, plus listed versions
4.6.1-2build14.6.1-2build2
None known
coturn
openSUSE:Tumbleweed
From an advisory covering 17 CVEs
before 4.17.2-1.1
4.17.2-1.1

History

History
RecordedChangedSources
affected, facts
first indexedCVE List, EUVD, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-62959 is a high vulnerability (CVSS 8.2) in Coturn, published July 31, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.52%, the 44th percentile. Fixed in coturn 4.15.0-1.

References

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