# btrfs: defrag: fix deadlock between defrag and delalloc space reservation

CVE record · `CVE-2026-90265`

- **Identifiers:** `CVE-2026-90265`
- **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, 16:08 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: `22b398eeeed43d51e85b1008e51bf9663ac1f491 to before 046396bd16fdf0a9fbdf5f04c6eda26024e7695e` (git)
  - affected: `22b398eeeed43d51e85b1008e51bf9663ac1f491 to before c97277aa6ce8ac725642aced0fe20cd8d31f6e09` (git)
  - affected: `22b398eeeed43d51e85b1008e51bf9663ac1f491 to before 37614074596827a5f292243673b699c90ff63e7d` (git)
  - affected: `22b398eeeed43d51e85b1008e51bf9663ac1f491 to before a9701dd06e82c345fe70debdf8835b7eb5000c59` (git)
  - affected: `22b398eeeed43d51e85b1008e51bf9663ac1f491 to before ac916391e1c70801649f7d6f85014f687983bc33` (git)
  - affected: `22b398eeeed43d51e85b1008e51bf9663ac1f491 to before ba02eab28041f9a4bbe9fc90c7249644fef6de0f` (git)
  - Other versions: unaffected
- Vendor: Linux. Product: Linux.
  - affected: `5.16`
  - unaffected: `before 5.16` (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 btrfs code is affected from 5.16 until fixed. Defrag can deadlock while reserving delalloc space with folios locked, hanging tasks. The source gives few details on attacker access, and the description is truncated. Upgrade to 6.1.191, 6.6.160, 6.12.114, 6.18.52, or a later release in those series.

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-2026-90265](https://www.cve.org/CVERecord?id=CVE-2026-90265)
- [NVD: CVE-2026-90265](https://nvd.nist.gov/vuln/detail/CVE-2026-90265)

### References from the CNA

- <https://git.kernel.org/stable/c/046396bd16fdf0a9fbdf5f04c6eda26024e7695e>
- <https://git.kernel.org/stable/c/c97277aa6ce8ac725642aced0fe20cd8d31f6e09>
- <https://git.kernel.org/stable/c/37614074596827a5f292243673b699c90ff63e7d>
- <https://git.kernel.org/stable/c/a9701dd06e82c345fe70debdf8835b7eb5000c59>
- <https://git.kernel.org/stable/c/ac916391e1c70801649f7d6f85014f687983bc33>
- <https://git.kernel.org/stable/c/ba02eab28041f9a4bbe9fc90c7249644fef6de0f>

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-2026-90265>
- Everything that needs attention now: <https://agentprime.io/advisories/critical.md>

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The web page: <https://agentprime.io/advisories/CVE-2026-90265/>. Everything for agents: <https://agentprime.io/llms.txt>.