8.2 High

The WireGuard VPN service in subsys/net/lib/wireguard/wg.c updated the peer endpoint from a message it could not authenticate.

CVE-2026-79977

The WireGuard VPN service in subsys/net/lib/wireguard/wg.c updated the peer endpoint from a message it could not authenticate. In handletransportdata(), when the 32-bit receiver index of an incoming transport-data message matched no session, the code both scheduled a new handshake and copied the datagram's source address into peer->endpoint with memcpy(&peer->endpoint, peeraddr, sizeof(peer->endpoint)). Because the receiver index is unknown, there is no key with which such a message could be verified, so the address written into peer->endpoint is entirely attacker-supplied. Every other endpoint update in the implementation happens only after authentication — after the Noise handshake in handlehandshakeinit(), or after AEAD decryption plus the anti-replay check in wgprocessdatamessage(). The WireGuard listener is registered with netudpregister() using no remote address or port filter and defaults to UDP port 51820 (CONFIGWIREGUARDPORT), and wgctrlrecv() resolves the peer by interface rather than by any cryptographic identity. Any host able to send a UDP datagram to that port can therefore reach the defect off-path, with no need to observe legitimate traffic: a 16-byte datagram…

Assessment

CVSS: 8.2 (v3.1)
Severity: High
EPSS: 0.2% chance of exploitation in the next 30 days
Known exploited: Not listed in CISA KEV
Exploit availability: Nothing found in Exploit-DB, Metasploit, Nuclei or public PoC repositories
Published: 23 October 2026
Last updated: 26 October 2026
Affected: zephyrproject
Weakness: CWE-306, CWE-346
Assigner: vulnerabilities@zephyrproject.org

CVSS vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H

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