CVE-2026-31696 (GCVE-0-2026-31696)

Vulnerability from cvelistv5 – Published: 2026-05-01 13:55 – Updated: 2026-05-01 13:55
VLAI?
Title
rxrpc: Fix missing validation of ticket length in non-XDR key preparsing
Summary
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 ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 8a7a3eb4ddbe7c7e639170a64adede7cbd5a9247 , < 1fa36cf495b0023e8475d038535c05e4063211e1 (git)
Affected: 8a7a3eb4ddbe7c7e639170a64adede7cbd5a9247 , < 4458757c020592a3094366e0fb20457383b42f92 (git)
Affected: 8a7a3eb4ddbe7c7e639170a64adede7cbd5a9247 , < ce383ba615339f8eaec646a166d2c2b015bb5ca0 (git)
Affected: 8a7a3eb4ddbe7c7e639170a64adede7cbd5a9247 , < a1be1c9ece26cea69654f28b255ff9a7906b897b (git)
Affected: 8a7a3eb4ddbe7c7e639170a64adede7cbd5a9247 , < ac33733b10b484d666f97688561670afd5861383 (git)
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    Linux Linux Affected: 3.17
Unaffected: 0 , < 3.17 (semver)
Unaffected: 6.6.136 , ≤ 6.6.* (semver)
Unaffected: 6.12.84 , ≤ 6.12.* (semver)
Unaffected: 6.18.25 , ≤ 6.18.* (semver)
Unaffected: 7.0.2 , ≤ 7.0.* (semver)
Unaffected: 7.1-rc1 , ≤ * (original_commit_for_fix)
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          "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 \u003c= 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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        },
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    "datePublished": "2026-05-01T13:55:57.485Z",
    "dateReserved": "2026-03-09T15:48:24.131Z",
    "dateUpdated": "2026-05-01T13:55:57.485Z",
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  }
}


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