{"id":"CVE-2026-98805","title":"tipc: prevent GCM nonce reuse on peer key changes","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\ntipc: prevent GCM nonce reuse on peer key changes\n\nTIPC can encrypt traffic between nodes using a different transmit key\nfor each node. In this mode, the AES-GCM nonce …","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= fc1b6d6de2208774efd2a20bf0daddb02d18b1e0 < 5c8ce13c792e28d56f9ec3cd6728d8225bc0e3a2","Linux >= fc1b6d6de2208774efd2a20bf0daddb02d18b1e0 < f74f100e49588c1dbdc6ab3ba9e2c67b36d015d0","Linux >= fc1b6d6de2208774efd2a20bf0daddb02d18b1e0 < 60e0c2aeaa605ff19ca4e65126a35643d4d7ee1c","Linux >= fc1b6d6de2208774efd2a20bf0daddb02d18b1e0 < 512ccd3d0e91e791fb37442aa0a2599aca19783d","Linux 5.5"],"published":"2026-10-18","updated":"2026-10-18","sourceUpdated":"2026-10-18T15:48:51.902Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98805","references":[{"url":"https://git.kernel.org/stable/c/5c8ce13c792e28d56f9ec3cd6728d8225bc0e3a2"},{"url":"https://git.kernel.org/stable/c/f74f100e49588c1dbdc6ab3ba9e2c67b36d015d0"},{"url":"https://git.kernel.org/stable/c/60e0c2aeaa605ff19ca4e65126a35643d4d7ee1c"},{"url":"https://git.kernel.org/stable/c/512ccd3d0e91e791fb37442aa0a2599aca19783d"}],"tags":["cve.org"],"ingestedAt":"2026-10-18T16:47:32.480Z","slug":"CVE-2026-98805","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\ntipc: prevent GCM nonce reuse on peer key changes\n\nTIPC can encrypt traffic between nodes using a different transmit key\nfor each node. In this mode, the AES-GCM nonce for a packet sent to a\nknown peer consists of a 32-bit prefix (a per-key salt XOR the peer's\naddress) followed by a 64-bit counter. That counter is stored in the\npeer's RX crypto object. When the peer reports a change in which key\nit uses to receive packets, TIPC resets this counter. The sender can\nstill be using the same TX key and salt, so subsequent packets reuse\nearlier nonces. This nonce reuse breaks confidentiality and exposes\nGCM's authentication key. This makes forgeries trivial: an attacker\ncan exploit CTR malleability to alter captured ciphertexts and use the\nrecovered authentication key to compute a valid tag for the modified\nciphertext, under the same key and nonce.\n\nUse the TX key's existing aead->seqno counter instead. All encryptions\nusing that key object share the same atomic counter, so concurrent\nencryptions get distinct nonce counter values. The counter survives\nkey activation and peer reconnection, and peer key-status reports\ncannot reset it. This prevents those transitions from causing nonce\nreuse while the same TX key remains installed.\n\nThe nonce format is unchanged, and receivers do not require consecutive\ncounter values, so sharing the counter across peers remains compatible\nwith existing receivers. A pre-existing check still invokes key\nrevocation in the unlikely event that the counter wraps to zero.\n\n## Affected\n\n- `Linux >= fc1b6d6de2208774efd2a20bf0daddb02d18b1e0 < 5c8ce13c792e28d56f9ec3cd6728d8225bc0e3a2`\n- `Linux >= fc1b6d6de2208774efd2a20bf0daddb02d18b1e0 < f74f100e49588c1dbdc6ab3ba9e2c67b36d015d0`\n- `Linux >= fc1b6d6de2208774efd2a20bf0daddb02d18b1e0 < 60e0c2aeaa605ff19ca4e65126a35643d4d7ee1c`\n- `Linux >= fc1b6d6de2208774efd2a20bf0daddb02d18b1e0 < 512ccd3d0e91e791fb37442aa0a2599aca19783d`\n- `Linux 5.5`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}