{"id":"CVE-2026-43187","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-43187","generatedAt":"2026-10-28T06:14:42.663Z","title":"In the Linux kernel, the following vulnerability has been resolved: xfs: delete attr leaf freemap entries when empty Back in commit 2a2b5932db6758 (\"xfs: fix attr leaf header freemap.size underflow\"), Brian Foster observed that it's possible for a small…","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nxfs: delete attr leaf freemap entries when empty\n\nBack in commit 2a2b5932db6758 (\"xfs: fix attr leaf header freemap.size\nunderflow\"), Brian Foster observed that it's possible for a small\nfreemap at the end of the end of the xattr entries array to experience\na size underflow when subtracting the space consumed by an expansion of\nthe entries array.  There are only three freemap entries, which means\nthat it is not a complete index of all free space in the leaf block.\n\nThis code can leave behind a zero-length freemap entry with a nonzero\nbase.  Subsequent setxattr operations can increase the base up to the\npoint that it overlaps with another freemap entry.  This isn't in and of\nitself a problem because the code in _leaf_add that finds free space\nignores any freemap entry with zero size.\n\nHowever, there's another bug in the freemap update code in _leaf_add,\nwhich is that it fails to update a freemap entry that begins midway\nthrough the xattr entry that was just appended to the array.  That can\nresult in the freemap containing two entries with the same base but\ndifferent sizes (0 for the \"pushed-up\" entry, nonzero for the entry\nthat's actually tracking free space).  A subsequent _leaf_add can then\nallocate xattr namevalue entries on top of the entries array, leading to\ndata loss.  But fixing that is for later.\n\nFor now, eliminate the possibility of confusion by zeroing out the base\nof any freemap entry that has zero size.  Because the freemap is not\nintended to be a complete index of free space, a subsequent failure to\nfind any free space for a new xattr will trigger block compaction, which\nregenerates the freemap.\n\nIt looks like this bug has been in the codebase for quite a long time.","published":"2026-05-06T12:16:37.000Z","lastModified":"2026-10-19T20:18:10.000Z","status":"Modified","sourceIdentifier":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","cvss":{"version":"3.1","score":8.8,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"},"cwe":["CWE-191","CWE-190"],"affected":["linux/linux kernel"],"epss":{"score":0.00469,"percentile":0.40374,"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 (0.47%). 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/479b05fc3ee272090f671b06a41f3da8aa78eece","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/6f13c1d2a6271c2e73226864a0e83de2770b6f34","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/a631899025d47ea1aa6464d76db5b4d3b6d196fd","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/aa9083d97e2157da3c6fb45ddb1a97af7f188f7f","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/e1b8c6452ee99a30e188a88f3f3f804fb1c6004a","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/f31a8334e1c54b126fcecf98645a49b6bc5ad399","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/f3c0d1fc1eadbb4adbee5ab7757d41d35f48325b","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/ffaf5c99d0f862db021fb1af8b813c1416b1beb2","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-43187","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."}