CVE-2025-21655
Last modified
CVE-2025-21655 is a medium-severity vulnerability rated 4.7/10 on the CVSS scale. In the Linux kernel, the following vulnerability has been resolved: io_uring/eventfd: ensure io_eventfd_signal() defers another RCU period io_eventfd_do_signal() is invoked from an RCU callback, but when dropping the reference to the io_ev_fd, it calls io_eventfd_free() directly if the refcount drops to zero. This isn't correct, as any potential freeing of the io_ev_fd should be deferred another RCU grace period. Just call io_eventfd_put() rather than open-code the dec-and-test and free, which will correctly defer it another RCU grace period.. EPSS estimates a 0.22% chance of exploitation in the next 30 days.
Description
In the Linux kernel, the following vulnerability has been resolved: io_uring/eventfd: ensure io_eventfd_signal() defers another RCU period io_eventfd_do_signal() is invoked from an RCU callback, but when dropping the reference to the io_ev_fd, it calls io_eventfd_free() directly if the refcount drops to zero. This isn't correct, as any potential freeing of the io_ev_fd should be deferred another RCU grace period. Just call io_eventfd_put() rather than open-code the dec-and-test and free, which will correctly defer it another RCU grace period.
Metrics
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
Weakness Enumeration
Affected Software
| Vendor | Product | Versions | Update |
|---|---|---|---|
| Linux | Linux Kernel | >= 6.1, < 6.1.125 | — |
| Linux | Linux Kernel | >= 6.2, < 6.6.72 | — |
| Linux | Linux Kernel | >= 6.7, < 6.12.10 | — |
| Linux | Linux Kernel | 6.13 | Rc1 |
References
- https://project-zero.issues.chromium.org/issues/388499293Issue Tracking, Third Party Advisory
Timeline
- Published
- Last Modified
- Status
- Modified
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- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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