# btrfs: fix incorrect return value after changing leaf in lookup_extent_data_ref()

CVE record · `CVE-2026-31666`

- **Identifiers:** `CVE-2026-31666`
- **State:** Confirmed
- **Severity:** CVSS 7.8 High
- **Critical:** No
- **CNA:** Linux
- **Weakness (CWE):** [CWE-754](https://cwe.mitre.org/data/definitions/754.html)
- **Tags:** [CWE-754](https://agentprime.io/advisories/tag/cwe-754.md)
- **Technologies:** [Linux kernel](https://agentprime.io/advisories/technology/linux-kernel.md)
- **Published:** 24 Apr 2026
- **Updated:** 19 Oct 2026
- **Reviewed by a person:** No

Published by the CVE Program (CNA: Linux) at 24 Apr 2026, 14:45 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: `1618aa3c2e0163f5ac34d514ae89474521910536 to before 4125a194db4a6cf91f619f38788272651cb97dce` (git)
  - affected: `1618aa3c2e0163f5ac34d514ae89474521910536 to before 450e6a685d0cad95b15f8af152057bd0bf79f50b` (git)
  - affected: `1618aa3c2e0163f5ac34d514ae89474521910536 to before ab1e022379c3c811aa72da8eb0c7507859a1d0f5` (git)
  - affected: `1618aa3c2e0163f5ac34d514ae89474521910536 to before 316fb1b3169efb081d2db910cbbfef445afa03b9` (git)
  - Other versions: unaffected
- Vendor: Linux. Product: Linux.
  - affected: `6.10`
  - unaffected: `before 6.10` (semver)
  - unaffected: `6.12.82 to 6.12.*, inclusive` (semver)
  - unaffected: `6.18.23 to 6.18.*, inclusive` (semver)
  - unaffected: `6.19.13 to 6.19.*, inclusive` (semver)
  - unaffected: `7.0 to *, inclusive` (original_commit_for_fix)
  - Other versions: affected

## 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

- 7.8 High, CVSS 3.1: `CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`, from CNA (Linux)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0012, the 1st percentile, on 8 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 24 Apr 2026. New records show when each source confirmed them.

## Sources

- [CVE List: CVE-2026-31666](https://www.cve.org/CVERecord?id=CVE-2026-31666)
- [NVD: CVE-2026-31666](https://nvd.nist.gov/vuln/detail/CVE-2026-31666)

### References from the CNA

- <https://git.kernel.org/stable/c/4125a194db4a6cf91f619f38788272651cb97dce>
- <https://git.kernel.org/stable/c/450e6a685d0cad95b15f8af152057bd0bf79f50b>
- <https://git.kernel.org/stable/c/ab1e022379c3c811aa72da8eb0c7507859a1d0f5>
- <https://git.kernel.org/stable/c/316fb1b3169efb081d2db910cbbfef445afa03b9>

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-2026-31666>
- Everything that needs attention now: <https://agentprime.io/advisories/critical.md>

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The web page: <https://agentprime.io/advisories/CVE-2026-31666/>. Everything for agents: <https://agentprime.io/llms.txt>.