{"id":"CVE-2026-80899","state":"PUBLISHED","title":"erofs: remove fscache backend entirely","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nerofs: remove fscache backend entirely\n\nEROFS over fscache was introduced to provide image lazy pulling\nfunctionality. After the feature landed, the fscache subsystem made\nnetfs a new hard dependency, which is unexpected for a local filesystem\nand has an kernel-defined caching hierarchy which could be inflexible\ncompared to the fanotify pre-content hooks. Therefore, this feature has\nbeen deprecated for almost two years.\n\nAs EROFS file-backed mounts and fanotify pre-content hooks both upstream\nfor a while and already providing equivalent functionality (erofs-utils\nhas supported fanotify pre-content hooks), let's remove the fscache\nbackend now.\n\nThe main application of this feature is Nydus [1], and they plan to move\nto use fanotify pre-content hooks in the near future too.\n\nI hope this patch can be merged into Linux 7.2, which is also motivated\nby newly found implementation issues [2][3] that are not worth\ninvestigating given the deprecation and limited development resources.\nThe associated fscache/cachefiles cleanup patch will follow separately\nthrough the vfs tree (netfs) later: it seems fine since the codebase is\nisolated by CONFIG_CACHEFILES_ONDEMAND.\n\n[1] https://github.com/dragonflyoss/nydus/blob/v2.1.0/docs/nydus-fscache.md\n[2] https://github.com/dragonflyoss/nydus/pull/1824\n[3] https://lore.kernel.org/r/20260619135800.1594811-1-michael.bommarito@gmail.com","publishedAt":"2026-09-04T17:11:14.158Z","updatedAt":"2026-09-07T14:21:26.371Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"a1bafc3109d713ed83f73d61ba5cb1e6fd80fdbc","status":"affected","lessThan":"f6145794f17a27d25f8a84edb80731fb0e07c196","versionType":"git"},{"version":"a1bafc3109d713ed83f73d61ba5cb1e6fd80fdbc","status":"affected","lessThan":"c37460cd9b2fcb61ec66b7eb4fde737e65ec2a56","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["Documentation/filesystems/erofs.rst","fs/erofs/Kconfig","fs/erofs/Makefile","fs/erofs/data.c","fs/erofs/fscache.c","fs/erofs/inode.c","fs/erofs/internal.h","fs/erofs/ishare.c","fs/erofs/super.c","fs/erofs/zdata.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.9","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.9","versionType":"semver"},{"version":"7.1.8","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":["Documentation/filesystems/erofs.rst","fs/erofs/Kconfig","fs/erofs/Makefile","fs/erofs/data.c","fs/erofs/fscache.c","fs/erofs/inode.c","fs/erofs/internal.h","fs/erofs/ishare.c","fs/erofs/super.c","fs/erofs/zdata.c"]}],"references":["https://git.kernel.org/stable/c/f6145794f17a27d25f8a84edb80731fb0e07c196","https://git.kernel.org/stable/c/c37460cd9b2fcb61ec66b7eb4fde737e65ec2a56"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:07.220Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/80xxx/CVE-2026-80899.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-80899","state":"PUBLISHED","datePublished":"2026-09-04T17:11:14.158Z","dateUpdated":"2026-09-07T14:21:26.371Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-26T14:34:25.800Z"},"containers":{"cna":{"title":"erofs: remove fscache backend entirely","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nerofs: remove fscache backend entirely\n\nEROFS over fscache was introduced to provide image lazy pulling\nfunctionality. After the feature landed, the fscache subsystem made\nnetfs a new hard dependency, which is unexpected for a local filesystem\nand has an kernel-defined caching hierarchy which could be inflexible\ncompared to the fanotify pre-content hooks. Therefore, this feature has\nbeen deprecated for almost two years.\n\nAs EROFS file-backed mounts and fanotify pre-content hooks both upstream\nfor a while and already providing equivalent functionality (erofs-utils\nhas supported fanotify pre-content hooks), let's remove the fscache\nbackend now.\n\nThe main application of this feature is Nydus [1], and they plan to move\nto use fanotify pre-content hooks in the near future too.\n\nI hope this patch can be merged into Linux 7.2, which is also motivated\nby newly found implementation issues [2][3] that are not worth\ninvestigating given the deprecation and limited development resources.\nThe associated fscache/cachefiles cleanup patch will follow separately\nthrough the vfs tree (netfs) later: it seems fine since the codebase is\nisolated by CONFIG_CACHEFILES_ONDEMAND.\n\n[1] https://github.com/dragonflyoss/nydus/blob/v2.1.0/docs/nydus-fscache.md\n[2] https://github.com/dragonflyoss/nydus/pull/1824\n[3] https://lore.kernel.org/r/20260619135800.1594811-1-michael.bommarito@gmail.com"}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"a1bafc3109d713ed83f73d61ba5cb1e6fd80fdbc","status":"affected","lessThan":"f6145794f17a27d25f8a84edb80731fb0e07c196","versionType":"git"},{"version":"a1bafc3109d713ed83f73d61ba5cb1e6fd80fdbc","status":"affected","lessThan":"c37460cd9b2fcb61ec66b7eb4fde737e65ec2a56","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["Documentation/filesystems/erofs.rst","fs/erofs/Kconfig","fs/erofs/Makefile","fs/erofs/data.c","fs/erofs/fscache.c","fs/erofs/inode.c","fs/erofs/internal.h","fs/erofs/ishare.c","fs/erofs/super.c","fs/erofs/zdata.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.9","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.9","versionType":"semver"},{"version":"7.1.8","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":["Documentation/filesystems/erofs.rst","fs/erofs/Kconfig","fs/erofs/Makefile","fs/erofs/data.c","fs/erofs/fscache.c","fs/erofs/inode.c","fs/erofs/internal.h","fs/erofs/ishare.c","fs/erofs/super.c","fs/erofs/zdata.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/f6145794f17a27d25f8a84edb80731fb0e07c196"},{"url":"https://git.kernel.org/stable/c/c37460cd9b2fcb61ec66b7eb4fde737e65ec2a56"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-09-07T14:21:26.371Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.9","versionEndExcluding":"7.1.8"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.9","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}