# CVE-2026-90434: isofs: release zisofs block pointer buffer head

> A memory leak in the Linux kernel's isofs filesystem allows local attackers to cause a denial of service by exhausting memory resources.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 17 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-102995, BELL-CVE-2026-90434, DEBIAN-CVE-2026-90434, GHSA-xwjp-h426-22vm, UBUNTU-CVE-2026-90434

## What is CVE-2026-90434?

CVE-2026-90434 is a memory corruption vulnerability in Linux, published on 17 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:

isofs: release zisofs block pointer buffer head

zisofs_fill_pages() reads the compressed block pointer table.  The error
paths release the current buffer_head, the loop also releases the old
buffer_head when it advances. However, the success path leaves the last
buffer_head referenced. Release it before returning success.

## Which versions are affected by CVE-2026-90434?


## How do I fix CVE-2026-90434?

Apply the vendor's patch.

## Is CVE-2026-90434 being exploited?

There is no known exploitation of CVE-2026-90434 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90434 and fix it if it is affected.

What it is: CVE-2026-90434 is a memory corruption vulnerability in Linux, published on 17 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-2026-90434 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-2026-90434/ (Markdown: https://insights.sbomify.com/CVE-2026-90434/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90434
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90434
- OSV: https://osv.dev/vulnerability/CVE-2026-90434

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90434/
Summaries are generated and may contain mistakes; the official description above is the record.