# CVE-2026-68448: ovl: check access to copy_file_range source with src mounter creds

> A local attacker can bypass read permission checks in overlayfs copy_file_range operations, potentially reading files they should not access.

- **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:** 12 Aug 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-95513, BELL-CVE-2026-68448, DEBIAN-CVE-2026-68448, GHSA-7vqh-66x8-88v7, UBUNTU-CVE-2026-68448

## What is CVE-2026-68448?

CVE-2026-68448 is a missing authorization vulnerability in Linux, published on 12 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:

ovl: check access to copy_file_range source with src mounter creds

Commit 5dae222a5ff0c ("vfs: allow copy_file_range to copy across devices")
allowed filesystems that implement the copy_file_range() f_op to decide
if they want to access cross-sb copy from/to the same fs type.

The same commit added checks to verify same sb copy for filesystems that
implement ->copy_file_range() and do not support cross-sb copy at the
time, namely, to ceph, fuse and nfs.

The two remaining fs which implement ->copy_file_range(), cifs and
overlayfs started to support cross-sb copy from this time.

While overlayfs does support cross-sb copy when the two underlying files
are on the same base fs, the copy operation on the two real files from
two different overalyfs filesystems is performed with the mounter
creds of the destination overlayfs and the read permission access hook
for the source file was called with the wrong creds.

This could cause either deny of access to copy which would otherwise be
allowed (e.g. with splice) or allow read access to file which would
otherwise be denied.

Fix the latter case by explicitly verifying read access to source file
with the source overlayfs mounter creds.

The former case remains a quirk of cross-sb overlayfs copy, but
userspace could fall back to regular copy so no harm done.

## Which versions are affected by CVE-2026-68448?


## How do I fix CVE-2026-68448?

Apply the vendor's patch.

## Is CVE-2026-68448 being exploited?

There is no known exploitation of CVE-2026-68448 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-68448 and fix it if it is affected.

What it is: CVE-2026-68448 is a missing authorization vulnerability in Linux, published on 12 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-2026-68448 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-2026-68448/ (Markdown: https://insights.sbomify.com/CVE-2026-68448/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-68448
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-68448
- OSV: https://osv.dev/vulnerability/CVE-2026-68448

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-68448/
Summaries are generated and may contain mistakes; the official description above is the record.