{"id":"CVE-2026-31696","title":"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 pay…","summary":"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 pay…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cwe":["CWE-787"],"vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 3.17, < 6.6.136","linux_kernel >= 6.7, < 6.12.84","linux_kernel >= 6.13, < 6.18.25","linux_kernel >= 6.19, < 7.0.2","linux_kernel = 7.1"],"patched":["linux_kernel 7.0.2"],"published":"2026-05-01","updated":"2026-10-15","sourceUpdated":"2026-10-15T02:19:17.777","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-31696","references":[{"url":"https://git.kernel.org/stable/c/1fa36cf495b0023e8475d038535c05e4063211e1","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/41a117dd80371343babc52198d1114e83eb37627","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/4458757c020592a3094366e0fb20457383b42f92","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/44714dfda386884919ba366411880b6fb3c3efd3","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/9a397aa9b5e53ca63d4d6aefb542832eca389618","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/a1be1c9ece26cea69654f28b255ff9a7906b897b","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/ac33733b10b484d666f97688561670afd5861383","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/ce383ba615339f8eaec646a166d2c2b015bb5ca0","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-784472.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"}],"tags":["nvd","cve.org"],"epss":0.00176,"epssPercentile":0.06635,"ingestedAt":"2026-10-15T03:30:12.865Z","slug":"CVE-2026-31696","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `linux_kernel >= 3.17, < 6.6.136`\n- `linux_kernel >= 6.7, < 6.12.84`\n- `linux_kernel >= 6.13, < 6.18.25`\n- `linux_kernel >= 6.19, < 7.0.2`\n- `linux_kernel = 7.1`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 7.0.2`","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}