# CVE-2026-99243: io-wq: order the exit bit against worker creation task work

Status: published. Published: 2026-11-03. Updated: 2026-11-03.

In the Linux kernel, the following vulnerability has been resolved:

io-wq: order the exit bit against worker creation task work

io_wq_exit_workers() cancels task work for queued worker creation with
task_work_cancel_match(). That has a plain load of task->task_works.

io_queue_worker_create() adds the new entry and tests IO_WQ_BIT_EXIT to
cancel it if the workqueue is already on its way out.

That must be ordered. task_work_add() has a full barrier via cmpxchg().
But io_wq_exit_start() sets the bit with set_bit() which doesn't have
any memory ordering.

So afaict, on weakly ordered architectures the exiting task may load
task_works before the store of the bit is visible. The other side tests
the bit before the store is visible as well. So the entry remains queued
with worker_refs and the exiting task waits on worker_done indefinitely.

If the task still has rings then io_uring_del_tctx_node() provides the
barrier via test_and_set_bit() in io_wq_set_exit_on_idle(). When it
has closed all rings though that barrier is gone.

Add the barrier after the set_bit().

## Remediation

No remediation reported in collected sources

## Affected products and versions

- Linux / Linux: ≥ 4b4e5bbf9386d4ec21d91c0cb0fd60b9bba778ec; < 67da3eec264aeb67835886720243ae2dc1463315 (affected, git); ≥ 71a85387546e50b1a37b0fa45dadcae3bfb35cf6; < a63c752157eacf49f628359822666b32503d194a (affected, git); ≥ 71a85387546e50b1a37b0fa45dadcae3bfb35cf6; < 1432d881d99584105122760133caeff1dce7a9f7 (affected, git); ≥ 71a85387546e50b1a37b0fa45dadcae3bfb35cf6; < 6cf012a4d5e461c788ecc9dbed67adc31a142644 (affected, git); ≥ 71a85387546e50b1a37b0fa45dadcae3bfb35cf6; < 0d81cdd433b0a96c5275c01b8172e0b1f71dd595 (affected, git); ≥ 71a85387546e50b1a37b0fa45dadcae3bfb35cf6; < 75395db7a9b40a2e826c838e648fef8ed1a2d174 (affected, git); ≥ 71a85387546e50b1a37b0fa45dadcae3bfb35cf6; < 31fc780b75b278d37700373d54a99fdb4117fdd6 (affected, git); ≥ 5.15.11; < 5.15.224 (affected, semver). Source: CNA: Linux
- Linux / Linux: 5.16 (affected); ≥ 0; < 5.16 (unaffected, semver); ≥ 5.15.224; ≤ 5.15.* (unaffected, semver); ≥ 6.1.191; ≤ 6.1.* (unaffected, semver); ≥ 6.6.161; ≤ 6.6.* (unaffected, semver); ≥ 6.12.115; ≤ 6.12.* (unaffected, semver); ≥ 6.18.60; ≤ 6.18.* (unaffected, semver); ≥ 7.2.14; ≤ 7.2.* (unaffected, semver); ≥ 7.3.1; ≤ 7.3.* (unaffected, semver). Source: CNA: Linux

## Severity and prioritization

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: Not reported

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://git.kernel.org/stable/c/67da3eec264aeb67835886720243ae2dc1463315 (CNA: Linux)

- https://git.kernel.org/stable/c/a63c752157eacf49f628359822666b32503d194a (CNA: Linux)

- https://git.kernel.org/stable/c/1432d881d99584105122760133caeff1dce7a9f7 (CNA: Linux)

- https://git.kernel.org/stable/c/6cf012a4d5e461c788ecc9dbed67adc31a142644 (CNA: Linux)

- https://git.kernel.org/stable/c/0d81cdd433b0a96c5275c01b8172e0b1f71dd595 (CNA: Linux)

- https://git.kernel.org/stable/c/75395db7a9b40a2e826c838e648fef8ed1a2d174 (CNA: Linux)

- https://git.kernel.org/stable/c/31fc780b75b278d37700373d54a99fdb4117fdd6 (CNA: Linux)

## Provenance

- CNA: Linux: https://www.cve.org/CVERecord?id=CVE-2026-99243; retrieved 2026-11-03; source updated 2026-11-03

Revision: 3232622a8e45e85b8a4f7e00067e79776336d13769ba445497d933d4d9c0a1e8

Canonical: https://y2.dev/cve/CVE-2026-99243

## Agent and API access

Public CVE pages, Markdown, and JSON are free to read without an account or API key.

- Public catalog: https://y2.dev/cve/index.json. Follow nextCursor with the same search, filters, sort, and limit (1–100). A null cursor marks the end.

- WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers.

- Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}.

- Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer <Y2_API_KEY>. Setup: https://y2.dev/docs/api/create-key.

- x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402.

- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

Collected public records only. Check source status for coverage and freshness.