# CVE-2026-80697: erofs: ensure valid f_path for page cache sharing

CVE-2026-80697 is fixed in linux on 1 platform by DEBIAN-CVE-2026-80697 (version 7.1.8-1), released August 29, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-80697
- Priority: Routine
- CVSS: 5.5 (Moderate)
- EPSS: 0.0020
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 28, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-80697

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 14 | 7.1.8-1 | [DEBIAN-CVE-2026-80697](https://patchblox.com/security/data/fix/linux/debian-cve-2026-80697.md) | Aug 29, 2026 |

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