# CVE-2026-89717: zram: set default primary compressor in zram_destroy_comps()

> A null pointer dereference in the Linux kernel zram module can cause a system crash when accessing compressor settings after destruction.

- **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:** 11 Sep 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-100539, BELL-CVE-2026-89717, DEBIAN-CVE-2026-89717, GHSA-5wpf-6ffc-hwm4, UBUNTU-CVE-2026-89717

## What is CVE-2026-89717?

CVE-2026-89717 is a vulnerability in Linux, published on 11 Sep 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:

zram: set default primary compressor in zram_destroy_comps()

Patch series "zram: fix zram issues reported by sashiko".

Sashiko drove by and reported [1] a couple of zram issues:
a possible BUG_ON() in zlib code due to missing winbits range
validation and one possible NULL-ptr dereference in zcomp.
Both are low risk yet still worth fixing.

This patch (of 2):

zram_destroy_comps() resets all compressors and leaves them set to NULL,
including the primary one, which is invalid device state, as now
comp_algorithm_show()->strcmp() can be called on a NULL compressor.  Set
default primary compressor in zram_destroy_comps().

## Which versions are affected by CVE-2026-89717?


## How do I fix CVE-2026-89717?

Apply the vendor's patch.

## Is CVE-2026-89717 being exploited?

There is no known exploitation of CVE-2026-89717 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89717 and fix it if it is affected.

What it is: CVE-2026-89717 is a vulnerability in Linux, published on 11 Sep 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-2026-89717 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-2026-89717/ (Markdown: https://insights.sbomify.com/CVE-2026-89717/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89717
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89717
- OSV: https://osv.dev/vulnerability/CVE-2026-89717

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89717/
Summaries are generated and may contain mistakes; the official description above is the record.