# CVE-2026-68147: fscrypt: Avoid dynamic allocation in fscrypt_get_devices()

> A use-after-free vulnerability in the Linux kernel's fscrypt module allows attackers to potentially execute code or cause a denial of service via dynamic allocation failures.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **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:** 10 Aug 2026
- **Updated:** 19 Aug 2026
- **Also known as:** BELL-CVE-2026-68147, DEBIAN-CVE-2026-68147, GHSA-m9pv-2424-h7vv, UBUNTU-CVE-2026-68147

## What is CVE-2026-68147?

CVE-2026-68147 is a high-severity use after free vulnerability in Linux, published on 10 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:

fscrypt: Avoid dynamic allocation in fscrypt_get_devices()

When a blk_crypto_key starts being used or is evicted, fs/crypto/ calls
fscrypt_get_devices() to get the filesystem's list of block devices,
then iterates over them and calls blk_crypto_config_supported(),
blk_crypto_start_using_key(), or blk_crypto_evict_key() on each one.

Currently, the block device pointers are placed in a dynamically
allocated array.  This dynamic allocation is problematic because:

- It can fail, especially at the fscrypt_destroy_inline_crypt_key() call
  site when it's invoked for inode eviction under direct reclaim.

- fscrypt_destroy_inline_crypt_key() doesn't handle the failure.  It
  just zeroizes and frees the blk_crypto_key without calling
  blk_crypto_evict_key().  That causes a use-after-free.

For now, let's fix this in the straightforward and easily-backportable
way by switching to an on-stack array.  Currently the fscrypt
multi-device functionality is used only by f2fs, which has a hardcoded
limit of 8 block devices.  An on-stack array works fine for that.

(Of course, this solution won't scale up to large number of block
devices.  For that we'd need a different solution, like moving the block
device iteration into the filesystem.  Or in the case of btrfs, which
will only support blk-crypto-fallback, we should make it just call
blk-crypto-fallback directly, so the block devices won't be needed.)

## Which versions are affected by CVE-2026-68147?


## How do I fix CVE-2026-68147?

Apply the vendor's patch.

## Is CVE-2026-68147 being exploited?

There is no known exploitation of CVE-2026-68147 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-68147 and fix it if it is affected.

What it is: CVE-2026-68147 is a high-severity use after free vulnerability in Linux, published on 10 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-2026-68147 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-2026-68147/ (Markdown: https://insights.sbomify.com/CVE-2026-68147/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-68147
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-68147
- OSV: https://osv.dev/vulnerability/CVE-2026-68147

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-68147/
Summaries are generated and may contain mistakes; the official description above is the record.