CVE-2026-98805 tipc: prevent GCM nonce reuse on peer key changes
An attacker on the network can decrypt and forge TIPC traffic due to nonce reuse when peer keys change, compromising confidentiality and integrity.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-98805?
CVE-2026-98805 is a vulnerability in Linux, published on 18 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
tipc: prevent GCM nonce reuse on peer key changes
TIPC can encrypt traffic between nodes using a different transmit key for each node. In this mode, the AES-GCM nonce for a packet sent to a known peer consists of a 32-bit prefix (a per-key salt XOR the peer's address) followed by a 64-bit counter. That counter is stored in the peer's RX crypto object. When the peer reports a change in which key it uses to receive packets, TIPC resets this counter. The sender can still be using the same TX key and salt, so subsequent packets reuse earlier nonces. This nonce reuse breaks confidentiality and exposes GCM's authentication key. This makes forgeries trivial: an attacker can exploit CTR malleability to alter captured ciphertexts and use the recovered authentication key to compute a valid tag for the modified ciphertext, under the same key and nonce.
Use the TX key's existing aead->seqno counter instead. All encryptions using that key object share the same atomic counter, so concurrent encryptions get distinct nonce counter values. The counter survives key activation and peer reconnection, and peer key-status reports cannot reset it. This prevents those transitions from causing nonce reuse while the same TX key remains installed.
The nonce format is unchanged, and receivers do not require consecutive counter values, so sharing the counter across peers remains compatible with existing receivers. A pre-existing check still invokes key revocation in the unlikely event that the counter wraps to zero.
Which versions are affected by CVE-2026-98805?
How do I fix CVE-2026-98805?
Apply the vendor's patch.
Is CVE-2026-98805 being exploited?
There is no known exploitation of CVE-2026-98805 in the wild and no public exploit code.
Sources
Also known as AZL-108590, BELL-CVE-2026-98805, DEBIAN-CVE-2026-98805, GHSA-c3cw-v3mg-q5gm, UBUNTU-CVE-2026-98805.