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CVE-2026-31696

Full vulnerability record from the local CVENow database.

Description

In the Linux kernel, the following vulnerability has been resolved: rxrpc: Fix missing validation of ticket length in non-XDR key preparsing In rxrpc_preparse(), there are two paths for parsing key payloads: the XDR path (for large payloads) and the non-XDR path (for payloads <= 28 bytes). While the XDR path (rxrpc_preparse_xdr_rxkad()) correctly validates the ticket length against AFSTOKEN_RK_TIX_MAX, the non-XDR path fails to do so. This allows an unprivileged user to provide a very large ticket length. When this key is later read via rxrpc_read(), the total token size (toksize) calculation results in a value that exceeds AFSTOKEN_LENGTH_MAX, triggering a WARN_ON(). [ 2001.302904] WARNING: CPU: 2 PID: 2108 at net/rxrpc/key.c:778 rxrpc_read+0x109/0x5c0 [rxrpc] Fix this by adding a check in the non-XDR parsing path of rxrpc_preparse() to ensure the ticket length does not exceed AFSTOKEN_RK_TIX_MAX, bringing it into parity with the XDR parsing logic.

Severity
HIGH
CVSS score
7.8 (v3.1)
Vulnerability status
Modified
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-05-01 14:16:19.403000
Last modified
2026-11-06 16:18:08.463000
View original CVE JSON 
{
  "id": "CVE-2026-31696",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2026-05-01T14:16:19.403",
  "lastModified": "2026-11-06T16:18:08.463",
  "vulnStatus": "Modified",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nrxrpc: Fix missing validation of ticket length in non-XDR key preparsing\n\nIn rxrpc_preparse(), there are two paths for parsing key payloads: the\nXDR path (for large payloads) and the non-XDR path (for payloads <= 28\nbytes). While the XDR path (rxrpc_preparse_xdr_rxkad()) correctly\nvalidates the ticket length against AFSTOKEN_RK_TIX_MAX, the non-XDR\npath fails to do so.\n\nThis allows an unprivileged user to provide a very large ticket length.\nWhen this key is later read via rxrpc_read(), the total\ntoken size (toksize) calculation results in a value that exceeds\nAFSTOKEN_LENGTH_MAX, triggering a WARN_ON().\n\n[ 2001.302904] WARNING: CPU: 2 PID: 2108 at net/rxrpc/key.c:778 rxrpc_read+0x109/0x5c0 [rxrpc]\n\nFix this by adding a check in the non-XDR parsing path of rxrpc_preparse()\nto ensure the ticket length does not exceed AFSTOKEN_RK_TIX_MAX,\nbringing it into parity with the XDR parsing logic."
    }
  ],
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      "affectedData": [
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          "product": "SIMATIC S7-1500 TM MFP - GNU/Linux subsystem",
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          "privilegesRequired": "LOW",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
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      "source": "[email protected]",
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          "value": "CWE-787"
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