{"id":"CVE-2026-63892","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-63892","generatedAt":"2026-10-28T09:42:15.659Z","title":"In the Linux kernel, the following vulnerability has been resolved: thunderbolt: property: Reject dir_len < 4 to prevent size_t underflow On the non-root path, __tb_property_parse_dir() takes dir_len from entry->length (u16 widened to size_t).","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nthunderbolt: property: Reject dir_len < 4 to prevent size_t underflow\n\nOn the non-root path, __tb_property_parse_dir() takes dir_len from\nentry->length (u16 widened to size_t).  Two distinct OOB conditions\nfollow when entry->length < 4:\n\n1. The non-root path begins with kmemdup(&block[dir_offset],\n   sizeof(*dir->uuid), ...) which always reads 4 dwords from\n   dir_offset.  tb_property_entry_valid() only enforces\n   dir_offset + entry->length <= block_len, so a crafted entry\n   with dir_offset close to the end of the property block and\n   entry->length in 0..3 passes that gate but lets the UUID copy\n   run off the block (e.g. dir_offset = 497, dir_len = 3 in a\n   500-dword block reads block[497..501]).\n\n2. After the kmemdup, content_len = dir_len - 4 underflows size_t\n   to ~SIZE_MAX, nentries becomes SIZE_MAX / 4, and the entry\n   walk runs OOB on each iteration until an entry fails\n   validation or the kernel oopses on an unmapped page.\n\nReject dir_len < 4 on the non-root path *before* the UUID kmemdup,\nwhich closes both holes.\n\nAlso move INIT_LIST_HEAD(&dir->properties) up to immediately after\nthe dir allocation so the new error-return path (and the existing\nuuid-alloc failure path) calling tb_property_free_dir() sees a\nwalkable list rather than the zero-initialized NULL next/prev that\nlist_for_each_entry_safe() would oops on.","published":"2026-07-19T16:17:07.000Z","lastModified":"2026-07-27T17:44:24.000Z","status":"Awaiting Analysis","sourceIdentifier":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","cvss":null,"cwe":[],"affected":[],"epss":{"score":0.00229,"percentile":0.13675,"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":"unknown","text":"Not yet scored. NVD analysis is pending; check back once CVSS and EPSS values are published."},"changes":[],"references":[{"url":"https://git.kernel.org/stable/c/37abc4504fa19d8f9f1e87792e8a2b8fdb308e40","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/3bec49ca55e08fb085cc4318f24b1b37eaab28cb","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/542a13890b742099c461d70920e97b14e568f6ec","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/5506c825f14d810f0690b1f4367cb7249ebb387a","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/d548179adcc87e1bc66b17e00352a1f536e76065","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/de21b59c29e31c5108ddc04210631bbfab81b997","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/de618299190b418291609e6921557253bd417e25","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/e2d4d51cf5785815fa4e91e0c019e3eb2506a84c","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-63892","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."}