{"id":"CVE-2026-98214","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nselinux: recheck intermediate backing files on mprotect()\n\nmprotect() can be used to bypass the SELinux checks that mmap() performs\nagainst the intermediate layers of a…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nselinux: recheck intermediate backing files on mprotect()\n\nmprotect() can be used to bypass the SELinux checks that mmap() performs\nagainst the intermediate layers of a…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= bc6c380c1159de52a252ed11f19a42c47f60a735 < 4d50ebe5a27724e020747ffd61a051dec67cb8ec","Linux >= 8bacd09f12c27710228562e4d13163e58c5f4a45 < 89376fbfdcc1a728e1775f98752cdd90b0930a00","Linux >= d844702198395d3f80222777030f69db6be6b709 < d127c7e1f3e1231d8ac8b2738e3f00bea12afe74","Linux >= 82544d36b1729153c8aeb179e84750f0c085d3b1 < c2bbb905af2293549651b614a52ad91e0b462b60","Linux >= 82544d36b1729153c8aeb179e84750f0c085d3b1 < 78fc54b934bfb2c18aad8154c7302067146946f9","Linux cd0e707a927a70cdfd8bc5a512a9719a87f5ed51","Linux >= 6.6.144 < 6.6.158","Linux >= 6.12.95 < 6.12.112","Linux >= 6.18.38 < 6.18.54","Linux >= 7.0.4 < 7.1","Linux 7.1"],"published":"2026-10-06","updated":"2026-10-06","sourceUpdated":"2026-10-06T09:18:07.943","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-98214","references":[{"url":"https://git.kernel.org/stable/c/4d50ebe5a27724e020747ffd61a051dec67cb8ec","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/78fc54b934bfb2c18aad8154c7302067146946f9","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/89376fbfdcc1a728e1775f98752cdd90b0930a00","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/c2bbb905af2293549651b614a52ad91e0b462b60","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/d127c7e1f3e1231d8ac8b2738e3f00bea12afe74","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd","cve.org"],"ingestedAt":"2026-10-06T08:50:17.441Z","slug":"CVE-2026-98214","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nselinux: recheck intermediate backing files on mprotect()\n\nmprotect() can be used to bypass the SELinux checks that mmap() performs\nagainst the intermediate layers of a stacked filesystem.\n\nmmap() checks every backing layer as the request descends through the\nstack.  mprotect() only has the lowest backing file in vma->vm_file, so it\nrechecks the top-level user and the lowest mounter, but skips the mounters\nof every layer in between.  With two nested overlayfs mounts and a policy\ndenying mounter_t -> middle_file_t:file { execute }, a direct\nmmap(PROT_EXEC) is denied:\n\n  avc:  denied  { execute } for  pid=71 comm=\"nested_exec\"\n    path=\"/payload\" dev=\"overlay\" ino=9\n    scontext=user_u:base_r:mounter_t\n    tcontext=user_u:object_r:middle_file_t tclass=file permissive=0\n\nwhile mmap(PROT_NONE) followed by mprotect(PROT_EXEC) succeeds.\n\nPreserve each intermediate path, mounter SID and file-description SID in\nthe backing-file security blob, copying the saved entries when another\nbacking layer is opened.  Allocate the array only for nested backing files,\nand release it and the path references in the backing_file_free hook.\n\nDuring mprotect(), recheck fd { use } and the requested inode permissions\nfor every saved mounter, and include the intermediate layers in the execmod\nchecks.  Policy for nested stacking may then need to grant intermediate\nmounters what a direct mmap() already requires, and execmod on intermediate\nlabels for binaries using text relocations.\n\nTested on arm64 QEMU with a small BusyBox initramfs and a purpose-built\nSELinux policy, on a mainline tree containing\ncommit f2381b546e7e (\"fs: fix user path of nested backing files\").\n\n[PM: subject tweak]\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}