CVE-2026-98805 (GCVE-0-2026-98805)
Vulnerability from cvelistv5
Published
2026-10-18 15:48
Modified
2026-10-21 12:57
Severity ?
Summary
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.
References
Impacted products
Vendor Product Version
Linux Linux Version: fc1b6d6de2208774efd2a20bf0daddb02d18b1e0
Version: fc1b6d6de2208774efd2a20bf0daddb02d18b1e0
Version: fc1b6d6de2208774efd2a20bf0daddb02d18b1e0
Version: fc1b6d6de2208774efd2a20bf0daddb02d18b1e0
Version: fc1b6d6de2208774efd2a20bf0daddb02d18b1e0
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{
  "containers": {
    "cna": {
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        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/tipc/crypto.c"
          ],
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        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.5"
            },
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              "version": "0",
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              "versionType": "semver"
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              "version": "6.12.113",
              "versionType": "semver"
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            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.56",
              "versionType": "semver"
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              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.10",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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              "negate": false,
              "operator": "OR"
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        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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 for a packet sent to a\nknown peer consists of a 32-bit prefix (a per-key salt XOR the peer\u0027s\naddress) followed by a 64-bit counter. That counter is stored in the\npeer\u0027s 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\u0027s 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\u0027s existing aead-\u003eseqno 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."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-21T12:57:07.090Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/a85a3dce4b6c73ddaa1e9725b906249744bf7cf2"
        },
        {
          "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"
        }
      ],
      "title": "tipc: prevent GCM nonce reuse on peer key changes",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98805",
    "datePublished": "2026-10-18T15:48:51.902Z",
    "dateReserved": "2026-09-25T10:25:14.371Z",
    "dateUpdated": "2026-10-21T12:57:07.090Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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