# CVE-2026-90262: btrfs: retry verity reads for not-uptodate Merkle folios

> A local attacker can cause persistent I/O errors in btrfs verity operations by triggering transient read failures, leading to denial of service.

- **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-102441, BELL-CVE-2026-90262, DEBIAN-CVE-2026-90262, GHSA-hxmf-49q3-qmv4, UBUNTU-CVE-2026-90262

## What is CVE-2026-90262?

CVE-2026-90262 is a denial of service 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:

btrfs: retry verity reads for not-uptodate Merkle folios

btrfs_read_merkle_tree_page() can find a folio in the mapping that is not
uptodate.  After taking the folio lock, the current code treats that state
as a read error and returns -EIO.

That can make a previous transient read failure sticky.  If the failed read
left a not-uptodate folio in the mapping, later callers find that folio and
fail instead of retrying the read.

Keep the existing page-cache insertion and locking order, but retry the
Merkle item read when a not-uptodate folio is found in the mapping.  Also
unlock the folio when read_key_bytes() fails so that a later caller can
lock it and retry the read.

## Which versions are affected by CVE-2026-90262?


## How do I fix CVE-2026-90262?

Apply the vendor's patch.

## Is CVE-2026-90262 being exploited?

There is no known exploitation of CVE-2026-90262 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90262 and fix it if it is affected.

What it is: CVE-2026-90262 is a denial of service 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-2026-90262 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-2026-90262/ (Markdown: https://insights.sbomify.com/CVE-2026-90262/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90262
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90262
- OSV: https://osv.dev/vulnerability/CVE-2026-90262

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90262/
Summaries are generated and may contain mistakes; the official description above is the record.