# 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.

- **Severity:** Not scored
- **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:** Yes
- **Published:** 28 Aug 2026
- **Updated:** 28 Aug 2026
- **Also known as:** DEBIAN-CVE-2026-80697, GHSA-qmfh-wqc6-r6c2, UBUNTU-CVE-2026-80697

## 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.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80697 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-80697 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-80697/ (Markdown: https://insights.sbomify.com/CVE-2026-80697/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80697
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80697
- OSV: https://osv.dev/vulnerability/CVE-2026-80697

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80697/
Summaries are generated and may contain mistakes; the official description above is the record.