In the Linux kernel, the following vulnerability has been resolved: freevxfs: don't BUG() on unknown typed-extent type vxfs_bmap_typed() handles… (CVE-2026-98872)

The Linux kernel freevxfs filesystem contained a vulnerability where the vxfs_bmap_typed() function handled only four typed-extent types and invoked BUG() in its default case. If an on-disk typed extent had an unknown type value, this would trigger a kernel BUG, causing a kernel crash. This flaw was reachable via the ioctl(FIBMAP) system call on regular files. The fix replaced the BUG() call with WARN_ON_ONCE() and returned 0, allowing the ioctl to fail gracefully without crashing the kernel.

The vulnerability could cause a kernel crash (kernel panic) when processing certain malformed or unexpected filesystem metadata on freevxfs filesystems. This could lead to denial of service on affected systems. There is no indication of code execution or privilege escalation from the provided data.

A fix is available that replaces the kernel BUG() call with WARN_ON_ONCE() and returns an error code to prevent kernel crashes. Users should update their Linux kernel to a version including this fix. Since no vendor advisory or patch link is provided, check the Linux kernel mailing lists or official kernel release notes for the patch and upgrade accordingly.