io_uring: defer eventfd signaling when queued from a wakeup handler (CVE-2026-80920) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-80920

io_uring: defer eventfd signaling when queued from a wakeup handler

Answer in brief

CVE-2026-80920 records a Unknown severity vulnerability in io_uring: defer eventfd signaling when queued from a wakeup handler. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 9, 2026Updated Sep 9, 2026Source checked Sep 9, 2026First seen by HOL Sep 9, 2026Material review Sep 9, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Linux/Linuxgeneric	>=21a091b970cdbcf3e8ff829234b51be6f9192766 <e22f4494cc9487d326e5e3067f33dea7c1e442b2 \|\| >=21a091b970cdbcf3e8ff829234b51be6f9192766 <b6bb334b0e9348887e3e55e1f494b0c3b8fbf59f \|\| >=21a091b970cdbcf3e8ff829234b51be6f9192766 <40b6ccf68731809ceb85c6e9f0f8f2ed61c7aa5a \|\| >=21a091b970cdbcf3e8ff829234b51be6f9192766 <cd305ee3633a45fcf5f3a5d83f99f3cb77d87b6e	e22f4494cc9487d326e5e3067f33dea7c1e442b2, b6bb334b0e9348887e3e55e1f494b0c3b8fbf59f, 40b6ccf68731809ceb85c6e9f0f8f2ed61c7aa5a, cd305ee3633a45fcf5f3a5d83f99f3cb77d87b6e
Linux/Linuxgeneric	6.1	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to e22f4494cc9487d326e5e3067f33dea7c1e442b2 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 9, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 9, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 9, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.