Bug 2509934 (CVE-2026-65981)

Summary: CVE-2026-65981 coturn: Coturn: Authorization bypass allows session takeover via MOBILITY-TICKET session resume
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
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Priority: high    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Coturn, an open-source implementation of TURN and STUN servers. An authenticated attacker who obtains a victim's MOBILITY-TICKET can exploit this vulnerability during a session resume. This allows the attacker to take over the victim's TURN (Traversal Using Relays around NAT) allocation. As a result, the attacker can receive and inject relayed network traffic, and consume the victim's allocated resources.
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Description OSIDB Bzimport 2026-07-31 22:01:35 UTC 
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.