CVE-2026-99051

Published Oct 23, 2026

Description

In the Linux kernel, the following vulnerability has been resolved: fsverity: RCU-delay the freeing of struct fsverity_info __fsverity_get_info() calls rhashtable_lookup_fast(), which just uses rcu_read_lock() and doesn't directly synchronize with fsverity_remove_info(). For the same inode this isn't a problem: its fsverity_info is removed only at inode eviction time or upon failure to enable verity, when the inode no longer needs its fsverity_info and it will no longer be accessed via that inode. However, this is broken and can cause a use-after-free for concurrent __fsverity_get_info() for *different* inodes. Those rely on following fsverity_info::rhash_head in the rhashtable under rcu_read_lock() only. They also use fsverity_info::inode to do the key comparison. Fix this by RCU-delaying the freeing of 'struct fsverity_info' after it's been removed from the rhashtable.

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References

Frequently Asked Questions

What is CVE-2026-99051? +
In the Linux kernel, the following vulnerability has been resolved: fsverity: RCU-delay the freeing of struct fsverity_info __fsverity_get_info() calls rhashtable_lookup_fast(), which just uses rcu_read_lock() and doesn't directly synchronize with fsverity_remove_info(). For the same inode this isn't a problem: its fsverity_info is removed only at inode eviction time or upon failure to enable verity, when the inode no longer needs its fsverity_info and it will no longer be accessed via that inode. However, this is broken and can cause a use-after-free for concurrent __fsverity_get_info() for *different* inodes. Those rely on following fsverity_info::rhash_head in the rhashtable under rcu_read_lock() only. They also use fsverity_info::inode to do the key comparison. Fix this by RCU-delaying the freeing of 'struct fsverity_info' after it's been removed from the rhashtable.
How do I check if I'm vulnerable to CVE-2026-99051? +
You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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