{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-31637",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2026-31637"
  ],
  "published": "2026-04-24T14:47:31Z",
  "summary": "rxrpc: reject undecryptable rxkad response tickets",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nrxrpc: reject undecryptable rxkad response tickets\n\nrxkad_decrypt_ticket() decrypts the RXKAD response ticket and then\nparses the buffer as plaintext without checking whether\ncrypto_skcipher_decrypt() succeeded.\n\nA malformed RESPONSE can therefore use a non-block-aligned ticket\nlength, make the decrypt operation fail, and still drive the ticket\nparser with attacker-controlled bytes.\n\nCheck the decrypt result and abort the connection with RXKADBADTICKET\nwhen ticket decryption fails.",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
    }
  ],
  "affected": [
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:12",
        "name": "linux"
      },
      "versions": [
        "1:6.1.47-1+rpt4"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-2712",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v6",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7l",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v8",
            "binary_version": "1:6.1.47-1+rpt4"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.1.47-1+rpt4": {
            "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e",
            "upstream_version": "6.1.47",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.1.175",
            "compiled_filter": false
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-31637"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/252157d939d179b5d767cb860ff8fa7f8723b67a"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/a75b3b361dd481d942c5f259a82d59718a41092c"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/b3a808cd0790b5075aaa2bc3588edf02cd71d352"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/47073aab8a3a5a7b41c9bd37d2a3dcbeeccd6c8a"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/a149dcae23309df9de1c3b6b5d468610ef5ab7de"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/22f6258e7b31dba9bf88dce4e3ee7f0f20072e60"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/58fcd1b156152613ba00a064a129fb69507ddd7d"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/fe4447cd95623b1cfacc15f280aab73a6d7340b2"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-05T13:16:28Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 9.8,
      "cvss_v3_severity": "Critical",
      "scenario": "AV:N - The vulnerable path is reached by remote RxRPC RESPONSE packets over UDP to a listening AF_RXRPC service connection.\nAC:L - An attacker can initiate the connection, receive the server challenge, and craft a non-block-aligned ticket plus matching response using an attacker-chosen session key; no race or uncontrolled condition is required.\nPR:N - The flaw is in the authentication handshake before client credentials are validated, so a network attacker needs no prior privileges or valid rxkad ticket.\nUI:N - Exploitation only requires sending protocol packets to the service; no victim user action is needed.\nS:U - The impact remains within the kernel/RxRPC service security authority and does not cross a VM, IOMMU, or similar security boundary.\nC:H - The bug can bypass rxkad authentication and let an unauthenticated peer access data exposed by a protected RxRPC service in the highest reasonable deployment.\nI:H - A forged authenticated connection can issue arbitrary service RPCs and choose/downgrade the connection security level, enabling unauthorized modification of protected service state.\nA:H - In a severe RxRPC service deployment, the same authentication bypass can be used to invoke destructive or service-disrupting authenticated operations repeatedly over the network."
    }
  }
}