{"id":"CVE-2026-72366","state":"PUBLISHED","title":"netfs: Fix netfs_create_write_req() to handle async cache object creation","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfs: Fix netfs_create_write_req() to handle async cache object creation\n\nnetfs_create_write_req() will skip caching if the fscache cookie is\ndisabled, but this is a problem because async cache object creation might\nnot have got far enough yet that has been enabled - thereby causing the\ncall to fscache_begin_write_operation() to be skipped.\n\nFix this by removing the checks on the cookie and delegating this to\nfscache_begin_write_operation().","publishedAt":"2026-08-15T05:56:04.016Z","updatedAt":"2026-10-21T12:44:41.841Z","severity":{"score":9.8,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"7b589a9b45ae32aa9d7bece597490e141198d7a6","status":"affected","lessThan":"aee03fbc8803a40d65e20f1af816a7219048a426","versionType":"git"},{"version":"7b589a9b45ae32aa9d7bece597490e141198d7a6","status":"affected","lessThan":"8ab75e445c161c4cb504aa98e20ce1dd1ecd8e9a","versionType":"git"},{"version":"7b589a9b45ae32aa9d7bece597490e141198d7a6","status":"affected","lessThan":"1188a9846fadeacf9d1430b528e5217f749d665b","versionType":"git"},{"version":"7b589a9b45ae32aa9d7bece597490e141198d7a6","status":"affected","lessThan":"dbd6f56d975b23241b7bbb11bb8f562af548a0aa","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/netfs/write_issue.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.11","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.11","versionType":"semver"},{"version":"6.12.114","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/netfs/write_issue.c"]}],"references":["https://git.kernel.org/stable/c/aee03fbc8803a40d65e20f1af816a7219048a426","https://git.kernel.org/stable/c/8ab75e445c161c4cb504aa98e20ce1dd1ecd8e9a","https://git.kernel.org/stable/c/1188a9846fadeacf9d1430b528e5217f749d665b","https://git.kernel.org/stable/c/dbd6f56d975b23241b7bbb11bb8f562af548a0aa"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:58.252Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/72xxx/CVE-2026-72366.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-72366","state":"PUBLISHED","datePublished":"2026-08-15T05:56:04.016Z","dateUpdated":"2026-10-21T12:44:41.841Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-09T03:40:39.922Z"},"containers":{"cna":{"title":"netfs: Fix netfs_create_write_req() to handle async cache object creation","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfs: Fix netfs_create_write_req() to handle async cache object creation\n\nnetfs_create_write_req() will skip caching if the fscache cookie is\ndisabled, but this is a problem because async cache object creation might\nnot have got far enough yet that has been enabled - thereby causing the\ncall to fscache_begin_write_operation() to be skipped.\n\nFix this by removing the checks on the cookie and delegating this to\nfscache_begin_write_operation()."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"7b589a9b45ae32aa9d7bece597490e141198d7a6","status":"affected","lessThan":"aee03fbc8803a40d65e20f1af816a7219048a426","versionType":"git"},{"version":"7b589a9b45ae32aa9d7bece597490e141198d7a6","status":"affected","lessThan":"8ab75e445c161c4cb504aa98e20ce1dd1ecd8e9a","versionType":"git"},{"version":"7b589a9b45ae32aa9d7bece597490e141198d7a6","status":"affected","lessThan":"1188a9846fadeacf9d1430b528e5217f749d665b","versionType":"git"},{"version":"7b589a9b45ae32aa9d7bece597490e141198d7a6","status":"affected","lessThan":"dbd6f56d975b23241b7bbb11bb8f562af548a0aa","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/netfs/write_issue.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.11","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.11","versionType":"semver"},{"version":"6.12.114","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/netfs/write_issue.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/aee03fbc8803a40d65e20f1af816a7219048a426"},{"url":"https://git.kernel.org/stable/c/8ab75e445c161c4cb504aa98e20ce1dd1ecd8e9a"},{"url":"https://git.kernel.org/stable/c/1188a9846fadeacf9d1430b528e5217f749d665b"},{"url":"https://git.kernel.org/stable/c/dbd6f56d975b23241b7bbb11bb8f562af548a0aa"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL"},"scenarios":[{"lang":"en","value":"AV:N - The bug is in netfs client write/cache coordination for CIFS, NFS+fscache, Ceph, AFS, and 9p. A malicious remote filesystem server can deliver file data and control protocol timing to drive async fscache object creation and subsequent kernel writeback over the network.\nAC:L - The attacker controls both sides of the race by interleaving reads and writes or triggering writeback while the fscache cookie is still in CREATING/LOOKING_UP; the async-creation window can be hit reliably with retries, not conditions outside attacker influence.\nPR:N - A malicious NFS/SMB/Ceph server needs no privileges on the victim client; once a fscache-enabled mount to that server exists, exploitation requires only ordinary file access or automated writeback, not real root or init-namespace capabilities.\nUI:N - After a triggering read from the remote server, kernel writeback can invoke netfs_writepages without further victim action; an attacker with file access can also drive the race directly through concurrent read/write syscalls.\nS:U - Impact is kernel heap/folio corruption during local pagecache I/O within the same kernel security authority; it does not inherently cross VM, container, IOMMU, or sandbox boundaries.\nC:H - Skipping fscache_begin_write_operation desynchronizes cache and writeback streams; the same netfs/fscache subsystem previously produced UAFs when PG_private_2 coordination failed, enabling disclosure via freed/reused folio memory.\nI:H - Inconsistent dual-stream write completion can free or reuse folios while still referenced, yielding heap corruption primitives that related netfs fscache bugs have leveraged for arbitrary kernel writes and privilege escalation.\nA:H - The related netfs fscache fix documented kernel oops, ceph caps warnings, RCU expedited stalls, and UAF crashes from this coordination failure class; skipping required cache setup can oops, panic, or hang the system during writeback."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-21T12:44:41.841Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"6.12.114"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"6.18.40"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"7.1.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}