# btrfs: qgroup: fix a wrong length calculation in qgroup_free_reserved_data()

CVE record · `CVE-2026-90259`

- **Identifiers:** `CVE-2026-90259`
- **State:** Confirmed
- **Severity:** No CVSS score
- **Critical:** No
- **CNA:** Linux
- **Technologies:** [Linux kernel](https://agentprime.io/advisories/technology/linux-kernel.md)
- **Published:** 17 Sept 2026
- **Updated:** 30 Oct 2026
- **Reviewed by a person:** No

Published by the CVE Program (CNA: Linux) at 17 Sept 2026, 16:07 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it.

## Affected products, as the CNA wrote them

- Vendor: Linux. Product: Linux.
  - affected: `bc42bda22345efdb5d8b578d1b4df2c6eaa85c58 to before 036e6c216be66a085da3a0519f1be5f3230b6e26` (git)
  - affected: `bc42bda22345efdb5d8b578d1b4df2c6eaa85c58 to before 202ac9e469b78817512921c5db05cc2140e4ca43` (git)
  - affected: `bc42bda22345efdb5d8b578d1b4df2c6eaa85c58 to before 34adc843c28e5cd1f533a1d64f51b0f756fdf945` (git)
  - affected: `bc42bda22345efdb5d8b578d1b4df2c6eaa85c58 to before e6edde29990af8064b9d12217ec03db231ccd55d` (git)
  - affected: `bc42bda22345efdb5d8b578d1b4df2c6eaa85c58 to before c4c136555ff90f1e2921cc42da43daac0ef9985e` (git)
  - affected: `bc42bda22345efdb5d8b578d1b4df2c6eaa85c58 to before 9102b179512e11644fb0489ae62010a09afa199c` (git)
  - Other versions: unaffected
- Vendor: Linux. Product: Linux.
  - affected: `4.13`
  - unaffected: `before 4.13` (semver)
  - unaffected: `6.1.191 to 6.1.*, inclusive` (semver)
  - unaffected: `6.6.160 to 6.6.*, inclusive` (semver)
  - unaffected: `6.12.114 to 6.12.*, inclusive` (semver)
  - unaffected: `6.18.52 to 6.18.*, inclusive` (semver)
  - unaffected: `7.2.6 to 7.2.*, inclusive` (semver)
  - unaffected: `7.3 to *, inclusive` (original_commit_for_fix)
  - Other versions: affected

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> The Linux kernel's btrfs qgroup code miscalculates a length when freeing reserved data, affecting versions from 4.13 until fixed. The source gives few details on the impact or what an attacker would need. Upgrade to 6.1.191 or later on 6.1, 6.6.160 or later on 6.6, 6.12.114 or later on 6.12, or 6.18.52 or later on 6.18.

Written 12 Nov 2026.

## Not analysed yet

We haven’t published our own analysis of this CVE. If a person reviews it, this page will say what’s affected and what has to be true for it to matter.

## Severity and exploitation

No source has published a CVSS score for this record yet.

- **CISA KEV:** Not listed.
- **EPSS:** 0.0021, the 11th percentile, on 13 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

This record came from the full history of the CVE Program, published 17 Sept 2026. New records show when each source confirmed them.

## Sources

- [CVE List: CVE-2026-90259](https://www.cve.org/CVERecord?id=CVE-2026-90259)
- [NVD: CVE-2026-90259](https://nvd.nist.gov/vuln/detail/CVE-2026-90259)

### References from the CNA

- <https://git.kernel.org/stable/c/036e6c216be66a085da3a0519f1be5f3230b6e26>
- <https://git.kernel.org/stable/c/202ac9e469b78817512921c5db05cc2140e4ca43>
- <https://git.kernel.org/stable/c/34adc843c28e5cd1f533a1d64f51b0f756fdf945>
- <https://git.kernel.org/stable/c/e6edde29990af8064b9d12217ec03db231ccd55d>
- <https://git.kernel.org/stable/c/c4c136555ff90f1e2921cc42da43daac0ef9985e>
- <https://git.kernel.org/stable/c/9102b179512e11644fb0489ae62010a09afa199c>

Facts on this page come from the CVE List as the CNA published them, with CVSS from the sources named above, CISA KEV and FIRST EPSS. Vendors, products and versions are shown as the CNA wrote them. We don’t reproduce the CVE’s description.

## Check whether this affects you

This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it. Compare the affected versions above with what you run.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), `get_advisory` returns this record and `search_advisories` finds related ones. Setup: <https://agentprime.io/mcp.md>
- As JSON: <https://api.agentprime.io/v1/advisories/CVE-2026-90259>
- Everything that needs attention now: <https://agentprime.io/advisories/critical.md>

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The web page: <https://agentprime.io/advisories/CVE-2026-90259/>. Everything for agents: <https://agentprime.io/llms.txt>.