Vulnerability · Published Jul 31, 2026 · Assigned by GitHub_M
CVE-2026-65981Coturn: MOBILITY-TICKET session-resume authorization bypass allows cross-user TURN allocation takeover
High 7.1
In plain English
A high-severity authorization bypass via user-controlled key in coturn from coturn. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 33% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Coturn is a free open source implementation of TURN and STUN Server. Prior to 4.15.0, a server using --mobility authenticates a resumed REFRESH request with the resuming user's credentials but does not verify that identity against the original allocation owner, allowing an authenticated attacker who obtains a victim MOBILITY-TICKET to receive and inject relayed traffic and consume the victim's quota. In the handle_turn_refresh resume branch, the victim allocation (orig_ss) is located solely by the attacker-controlled mobile id, and credentials are only adopted (via copy_auth_parameters) when the resuming session is unauthenticated. Because the attacker's session already has hmackey_set set to 1 from its own prior authentication (which is never reset for long-term-credential sessions), the credential copy is skipped and check_stun_auth validates the REFRESH against the attacker's own identity rather than the allocation owner's. This issue is fixed in version 4.15.0.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | coturn | no fix listed | DEBIAN-CVE-2026-65981 |
| Debian:13 | coturn | no fix listed | DEBIAN-CVE-2026-65981 |
| Debian:14 | coturn | 4.15.0-1 | DEBIAN-CVE-2026-65981 |
| Ubuntu:22.04:LTS | coturn | no fix listed | UBUNTU-CVE-2026-65981 |
| Ubuntu:24.04:LTS | coturn | no fix listed | UBUNTU-CVE-2026-65981 |
| Ubuntu:26.04:LTS | coturn | no fix listed | UBUNTU-CVE-2026-65981 |
| Ubuntu:26.10 | coturn | no fix listed | UBUNTU-CVE-2026-65981 |
Affected products (as reported)
Weakness: CWE-639 · Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:L