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CVE-2026-80920— io_uring: defer eventfd signaling when queued from a wakeup handler

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

在 Linux 内核中，以下漏洞已得到解决： io_uring: 当从唤醒处理程序中排队时，延迟 eventfd 信号发送 在将第一个条目推入 时，会内联地触发 CQ 环的 eventfd 信号。对于采用 模式的环形缓冲区，这种添加操作通常发生在等待队列的唤醒处理程序中，此时持有某个任意等待队列的锁。 仅在 标志位被设置时才会拒绝递归调用，而该标志位本身正是由 设置的。如果唤醒链路的起点在别处，则信号会被内联发出，并可能反馈回 epoll。 为此，新增 标志，并在来自三个等待队列回调的 task_work 添加操作

AI Predicted 4.4 Difficulty: Hard

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 10

VendorProduct Version RangeStatus
Linux Linux 21a091b970cdbcf3e8ff829234b51be6f9192766< e22f4494cc9487d326e5e3067f33dea7c1e442b2 affected
21a091b970cdbcf3e8ff829234b51be6f9192766< b6bb334b0e9348887e3e55e1f494b0c3b8fbf59f affected
21a091b970cdbcf3e8ff829234b51be6f9192766< 40b6ccf68731809ceb85c6e9f0f8f2ed61c7aa5a affected
21a091b970cdbcf3e8ff829234b51be6f9192766< cd305ee3633a45fcf5f3a5d83f99f3cb77d87b6e affected
6.1 affected
< 6.1 unaffected
6.18.49≤ 6.18.* unaffected
7.1.11≤ 7.1.* unaffected
… +2 more rows
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I. Basic Information for CVE-2026-80920

Vulnerability Information
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Vulnerability Title
io_uring: defer eventfd signaling when queued from a wakeup handler
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 21a091b970cdbcf3e8ff829234b51be6f9192766 ~ e22f4494cc9487d326e5e3067f33dea7c1e442b2 -
Linux Linux 6.1 -

II. Public POCs for CVE-2026-80920

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III. Intelligence Information for CVE-2026-80920

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Patches & Fixes for CVE-2026-80920 (4)

Same Patch Batch · Linux · 2026-09-09 · 12 CVEs total

CVE-2026-80925 vlan: fix skb_under_panic and races when toggling HW VLAN offload
CVE-2026-80924 crypto: krb5 - use kfree_sensitive() for derived key buffers
CVE-2026-80923 xhci: dbgtty: Fix unregister on tty_register_driver() failure
CVE-2026-80922 crypto: qcom-rng - Allow zero as a random number
CVE-2026-80921 KVM: s390: vsie: zero stale crypto bits
CVE-2026-80919 drm/amdgpu: fix recursive ww_mutex acquire in amdgpu_devcoredump_format
CVE-2026-80918 HID: core: fix number/pointer type confusion on long items
CVE-2026-80917 PCI: host-generic: Fix NULL pointer dereference on 32-bit CAM systems
CVE-2026-80916 kcov: fix data corruption and race conditions on PREEMPT_RT
CVE-2026-80915 drm/xe: Fix DPT allocation paths.
CVE-2026-80914 Bluetooth: ISO: fix use-after-free of listener socket in iso_conn_ready

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-80920

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