# zram: fix out-of-bounds access in writeback_store()

CVE record · `CVE-2026-89718`

- **Identifiers:** `CVE-2026-89718`
- **State:** Confirmed
- **Severity:** No CVSS score
- **Critical:** No
- **CNA:** Linux
- **Technologies:** [Linux kernel](https://agentprime.io/advisories/technology/linux-kernel.md)
- **Published:** 11 Sept 2026
- **Updated:** 30 Oct 2026
- **Reviewed by a person:** No

Published by the CVE Program (CNA: Linux) at 11 Sept 2026, 19:46 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: `a939888ec38bf1f33e4a903056677e92a4844244 to before f1c5611f699a3aa2a85ebd5fec03dc9bc501e6d0` (git)
  - affected: `a939888ec38bf1f33e4a903056677e92a4844244 to before c2745e657f0974871fbc60d46d48c2b04e581330` (git)
  - affected: `a939888ec38bf1f33e4a903056677e92a4844244 to before 4d82d60178b02797dbe529e01ac211b26670c49f` (git)
  - affected: `a939888ec38bf1f33e4a903056677e92a4844244 to before ef073edd7cfd31aeb90eeab23273102c601f4d8e` (git)
  - affected: `a939888ec38bf1f33e4a903056677e92a4844244 to before 07a82a66f8c1894d92e51d97542c32ebf2c51b09` (git)
  - affected: `a939888ec38bf1f33e4a903056677e92a4844244 to before 894913e2d35c46ff19a77530907771ae57862b96` (git)
  - Other versions: unaffected
- Vendor: Linux. Product: Linux.
  - affected: `5.0`
  - unaffected: `before 5.0` (semver)
  - unaffected: `6.1.191 to 6.1.*, inclusive` (semver)
  - unaffected: `6.6.160 to 6.6.*, inclusive` (semver)
  - unaffected: `6.12.111 to 6.12.*, inclusive` (semver)
  - unaffected: `6.18.57 to 6.18.*, inclusive` (semver)
  - unaffected: `7.2.4 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.

> Linux kernel zram, affected since 5.0 until fixed, can perform out-of-bounds table accesses in writeback_store() if the device is reinitialized with a smaller disksize while a writeback request waits for a lock. The source gives few details on who can trigger this or the full impact. Upgrade to 6.1.191, 6.6.160, 6.12.111, 6.18.57 or a later release for your branch.

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:** 0.0017, the 6th percentile, on 14 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 11 Sept 2026. New records show when each source confirmed them.

## Sources

- [CVE List: CVE-2026-89718](https://www.cve.org/CVERecord?id=CVE-2026-89718)
- [NVD: CVE-2026-89718](https://nvd.nist.gov/vuln/detail/CVE-2026-89718)

### References from the CNA

- <https://git.kernel.org/stable/c/f1c5611f699a3aa2a85ebd5fec03dc9bc501e6d0>
- <https://git.kernel.org/stable/c/c2745e657f0974871fbc60d46d48c2b04e581330>
- <https://git.kernel.org/stable/c/4d82d60178b02797dbe529e01ac211b26670c49f>
- <https://git.kernel.org/stable/c/ef073edd7cfd31aeb90eeab23273102c601f4d8e>
- <https://git.kernel.org/stable/c/07a82a66f8c1894d92e51d97542c32ebf2c51b09>
- <https://git.kernel.org/stable/c/894913e2d35c46ff19a77530907771ae57862b96>

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-2026-89718>
- Everything that needs attention now: <https://agentprime.io/advisories/critical.md>

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The web page: <https://agentprime.io/advisories/CVE-2026-89718/>. Everything for agents: <https://agentprime.io/llms.txt>.