CVE-2026-80899 is a vulnerability in Linux Kernel
Published on September 4, 2026
erofs: remove fscache backend entirely
In the Linux kernel, the following vulnerability has been resolved:
erofs: remove fscache backend entirely
EROFS over fscache was introduced to provide image lazy pulling
functionality. After the feature landed, the fscache subsystem made
netfs a new hard dependency, which is unexpected for a local filesystem
and has an kernel-defined caching hierarchy which could be inflexible
compared to the fanotify pre-content hooks. Therefore, this feature has
been deprecated for almost two years.
As EROFS file-backed mounts and fanotify pre-content hooks both upstream
for a while and already providing equivalent functionality (erofs-utils
has supported fanotify pre-content hooks), let's remove the fscache
backend now.
The main application of this feature is Nydus [1], and they plan to move
to use fanotify pre-content hooks in the near future too.
I hope this patch can be merged into Linux 7.2, which is also motivated
by newly found implementation issues [2][3] that are not worth
investigating given the deprecation and limited development resources.
The associated fscache/cachefiles cleanup patch will follow separately
through the vfs tree (netfs) later: it seems fine since the codebase is
isolated by CONFIG_CACHEFILES_ONDEMAND.
[1] https://github.com/dragonflyoss/nydus/blob/v2.1.0/docs/nydus-fscache.md
[2] https://github.com/dragonflyoss/nydus/pull/1824
[3] https://lore.kernel.org/r/20260619135800.1594811-1-michael.bommarito@gmail.com
Products Associated with CVE-2026-80899
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Affected Versions
Linux:- Version 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and below f6145794f17a27d25f8a84edb80731fb0e07c196 is affected.
- Version 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and below c37460cd9b2fcb61ec66b7eb4fde737e65ec2a56 is affected.
- Before 7.1.8 is affected.
- Version 7.1.8, <= 7.1.* is unaffected.
- Version 7.2, <= * is unaffected.