In this flaw the TIPC subsystem in the Linux kernel improperly handles nonce generation for AES‑GCM when a peer reports a key change. The counter used for the 64‑bit nonce portion is reset, while the same transmit key and per‑key salt remain unchanged, causing the same nonce to be reused on subsequent packets. This break in the nonce uniqueness property of GCM leaks the authentication key and enables an attacker to modify ciphertexts using CTR malleability and generate a valid tag for the tampered packets, effectively providing full forgery capability and compromising confidentiality and integrity of TIPC traffic.

The affected product is the Linux kernel’s TIPC implementation. Any kernel build that has not incorporated the fix in the specified commit and that uses TIPC with per‑node encryption is vulnerable. The vendor list indicates Linux:Linux, and the CPE points to the generic Linux kernel. Specific version ranges are not supplied, so administrators should research to determine whether their kernel contains the fix corresponding to this commit.

Risk is high because the attacker can obtain the GCM authentication key and forge messages without authentication, with a CVSS score of 7.4. Though the EPSS score of <1% indicates an extremely low probability of exploitation and the issue is not listed in the CISA KEV catalog, the severity implied by key exposure and forgery makes this a critical flaw. The likely attack vector is a network attacker capable of participating in or observing a TIPC mesh, potentially remotely injecting or replaying packets if TIPC traffic is unencrypted or weakly protected.