{"id":"CVE-2026-72132","state":"PUBLISHED","title":"NFS: Charge unstable writes by request size, not folio size","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nNFS: Charge unstable writes by request size, not folio size\n\nnfs_folio_mark_unstable() and nfs_folio_clear_commit() charge and\nuncharge NR_WRITEBACK/WB_WRITEBACK by folio_nr_pages(folio) once per\n*request* added to or removed from a commit list. This is correct only\nwhen a folio has a single associated request. When pg_test splits a\nfolio into N sub-folio requests (e.g. pNFS flexfiles striping with a\nstripe unit smaller than the folio size, or plain wsize-limited\nsplitting), each of the N requests independently charges the whole\nfolio's page count, inflating the accounting by a factor of N per\nfolio. With large folios and small stripe units this reaches multiple\norders of magnitude: a 2 MiB folio split into 512 4 KiB requests can\ncharge up to 512x its real size, pushing global dirty+writeback\naccounting past the system's dirty threshold and forcing every\nbuffered writer on the host into the hard-throttle path, including\nunrelated in-kernel NFS server threads sharing the box.\n\nCharge each request only for the pages it actually covers.","publishedAt":"2026-08-15T05:53:08.096Z","updatedAt":"2026-08-17T05:08:49.516Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"0c493b5cf16e28d761b6e77c7c32aa0e7af70813","status":"affected","lessThan":"a442c258320b689f13d2205eaeeddf8b0e630288","versionType":"git"},{"version":"0c493b5cf16e28d761b6e77c7c32aa0e7af70813","status":"affected","lessThan":"1f646e23372f3444dc5f0bcb5404a49d26756add","versionType":"git"},{"version":"0c493b5cf16e28d761b6e77c7c32aa0e7af70813","status":"affected","lessThan":"0ffc032294a29601b1019dba91aa1a930d90df17","versionType":"git"},{"version":"0c493b5cf16e28d761b6e77c7c32aa0e7af70813","status":"affected","lessThan":"a192b6c149c6ea10cc88869accb78165eb454456","versionType":"git"},{"version":"0c493b5cf16e28d761b6e77c7c32aa0e7af70813","status":"affected","lessThan":"27934d02cbeb8a957dd11c985a579e58d30c5270","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfs/internal.h","fs/nfs/pnfs_nfs.c","fs/nfs/write.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.3","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.3","versionType":"semver"},{"version":"6.6.148","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.97","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.40","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.5","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfs/internal.h","fs/nfs/pnfs_nfs.c","fs/nfs/write.c"]}],"references":["https://git.kernel.org/stable/c/a442c258320b689f13d2205eaeeddf8b0e630288","https://git.kernel.org/stable/c/1f646e23372f3444dc5f0bcb5404a49d26756add","https://git.kernel.org/stable/c/0ffc032294a29601b1019dba91aa1a930d90df17","https://git.kernel.org/stable/c/a192b6c149c6ea10cc88869accb78165eb454456","https://git.kernel.org/stable/c/27934d02cbeb8a957dd11c985a579e58d30c5270"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:58.252Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/72xxx/CVE-2026-72132.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-72132","state":"PUBLISHED","datePublished":"2026-08-15T05:53:08.096Z","dateUpdated":"2026-08-17T05:08:49.516Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-09T03:40:39.907Z"},"containers":{"cna":{"title":"NFS: Charge unstable writes by request size, not folio size","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nNFS: Charge unstable writes by request size, not folio size\n\nnfs_folio_mark_unstable() and nfs_folio_clear_commit() charge and\nuncharge NR_WRITEBACK/WB_WRITEBACK by folio_nr_pages(folio) once per\n*request* added to or removed from a commit list. This is correct only\nwhen a folio has a single associated request. When pg_test splits a\nfolio into N sub-folio requests (e.g. pNFS flexfiles striping with a\nstripe unit smaller than the folio size, or plain wsize-limited\nsplitting), each of the N requests independently charges the whole\nfolio's page count, inflating the accounting by a factor of N per\nfolio. With large folios and small stripe units this reaches multiple\norders of magnitude: a 2 MiB folio split into 512 4 KiB requests can\ncharge up to 512x its real size, pushing global dirty+writeback\naccounting past the system's dirty threshold and forcing every\nbuffered writer on the host into the hard-throttle path, including\nunrelated in-kernel NFS server threads sharing the box.\n\nCharge each request only for the pages it actually covers."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"0c493b5cf16e28d761b6e77c7c32aa0e7af70813","status":"affected","lessThan":"a442c258320b689f13d2205eaeeddf8b0e630288","versionType":"git"},{"version":"0c493b5cf16e28d761b6e77c7c32aa0e7af70813","status":"affected","lessThan":"1f646e23372f3444dc5f0bcb5404a49d26756add","versionType":"git"},{"version":"0c493b5cf16e28d761b6e77c7c32aa0e7af70813","status":"affected","lessThan":"0ffc032294a29601b1019dba91aa1a930d90df17","versionType":"git"},{"version":"0c493b5cf16e28d761b6e77c7c32aa0e7af70813","status":"affected","lessThan":"a192b6c149c6ea10cc88869accb78165eb454456","versionType":"git"},{"version":"0c493b5cf16e28d761b6e77c7c32aa0e7af70813","status":"affected","lessThan":"27934d02cbeb8a957dd11c985a579e58d30c5270","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfs/internal.h","fs/nfs/pnfs_nfs.c","fs/nfs/write.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.3","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.3","versionType":"semver"},{"version":"6.6.148","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.97","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.40","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.5","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfs/internal.h","fs/nfs/pnfs_nfs.c","fs/nfs/write.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/a442c258320b689f13d2205eaeeddf8b0e630288"},{"url":"https://git.kernel.org/stable/c/1f646e23372f3444dc5f0bcb5404a49d26756add"},{"url":"https://git.kernel.org/stable/c/0ffc032294a29601b1019dba91aa1a930d90df17"},{"url":"https://git.kernel.org/stable/c/a192b6c149c6ea10cc88869accb78165eb454456"},{"url":"https://git.kernel.org/stable/c/27934d02cbeb8a957dd11c985a579e58d30c5270"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-17T05:08:49.516Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.3","versionEndExcluding":"6.6.148"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.3","versionEndExcluding":"6.12.97"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.3","versionEndExcluding":"6.18.40"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.3","versionEndExcluding":"7.1.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.3","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}