CVE-2026-53381: virtiofs: fix UAF on submount umount

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-19 · updated 2026-10-19
Weakness: CWE-416

Description

In the Linux kernel, the following vulnerability has been resolved: virtiofs: fix UAF on submount umount iput() called from fuse_release_end() can Oops if the super block has already been destroyed. Normally this is prevented by waiting for num_waiting to go down to zero before commencing with super block shutdown. This only works, however, for the last submount instance, as the wait counter is per connection, not per superblock. Revert to using synchronous release requests for the auto_submounts case, which is virtiofs only at this time.

Affected products

Linux kernel: from 5.10.246 before 5.10.260; from 5.15.196 before 5.15.211; from 6.1.158 before 6.1.177; from 6.6.115 before 6.6.144; from 6.12.54 before 6.12.95; from 6.17.4 before 6.18.37 — fixed in 5.10.260, 5.15.211, 6.1.177, 6.12.95, 6.18.37, 6.6.144

How to fix

Upgrade to a fixed version: Linux kernel 5.10.260, 5.15.211, 6.1.177, 6.12.95. Check the vendor advisory for mitigations.

References

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