CVE-2026-80697 erofs: ensure valid f_path for page cache sharing
A local attacker can trigger a kernel crash via null pointer dereference in EROFS page cache sharing when using mincore.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-80697?
CVE-2026-80697 is a vulnerability in Linux, published on 28 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
erofs: ensure valid f_path for page cache sharing
Previously, backing files for page cache sharing were set up with f_path left as NULL (only f_inode was valid). It worked, but a recent mincore fix relies on f_path.mnt and crashes (found by "erofs/028" on 7.2-rc4):
BUG: kernel NULL pointer dereference, address: 0000000000000018 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: Oops: 0000 [#1] SMP PTI CPU: 3 UID: 0 PID: 675528 Comm: fincore Not tainted 7.2.0-rc4-00002-g[]-dirty #1 PREEMPT(lazy) Hardware name: Red Hat KVM, BIOS 1.16.0-4.al8 04/01/2014 RIP: 0010:__do_sys_mincore+0xc0/0x2c0 ...
Specify valid paths using valid disconnected dentries together with erofs_ishare_mnt instead of leaving f_path empty, so they are more like real backing files in a pseudo filesystem and standard backing_file_open() can be used directly.
Which versions are affected by CVE-2026-80697?
How do I fix CVE-2026-80697?
Apply the vendor's patch.
Is CVE-2026-80697 being exploited?
There is no known exploitation of CVE-2026-80697 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-80697, GHSA-qmfh-wqc6-r6c2, UBUNTU-CVE-2026-80697.