{"id":"CVE-2026-31696","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-31696","generatedAt":"2026-10-28T04:46:30.819Z","title":"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…","description":"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.","published":"2026-05-01T14:16:19.000Z","lastModified":"2026-10-15T02:19:18.000Z","status":"Modified","sourceIdentifier":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","cvss":{"version":"3.1","score":7.8,"severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"},"cwe":["CWE-787"],"affected":["linux/linux kernel"],"epss":{"score":0.00135,"percentile":0.02938,"date":"2026-10-27","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.14%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://git.kernel.org/stable/c/1fa36cf495b0023e8475d038535c05e4063211e1","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/41a117dd80371343babc52198d1114e83eb37627","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/4458757c020592a3094366e0fb20457383b42f92","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/44714dfda386884919ba366411880b6fb3c3efd3","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/9a397aa9b5e53ca63d4d6aefb542832eca389618","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/a1be1c9ece26cea69654f28b255ff9a7906b897b","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/ac33733b10b484d666f97688561670afd5861383","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/ce383ba615339f8eaec646a166d2c2b015bb5ca0","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-784472.html","source":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-31696","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}