io_uring/eventfd: ensure io_eventfd_signal() defers another RCU period
Priority LOW 34CWE-416Published · Updated
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Code execution
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-416 and the CVSS impact.
Summary
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.
Why it matters now
EPSS 0.00253 16th percentileScored 2026-11-07
Fix Fixed Linux (Linux): 6.1.125, 6.6.72, 6.12.10 +1Red Hat: 1 advisory
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Linux | Linux | 6.1 and later | 6.1.125, 6.6.72, 6.12.10, 6.13 | Patch available | CNA |
- Linux VendorLinux Affected 6.1 and later Fixed in 6.1.125, 6.6.72, 6.12.10, 6.13 Patch available CNA
CPE configurations NVD · 7
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | 6.1 to before 6.1.125; 6.2 to before 6.6.72; 6.7 to before 6.12.10 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:6.13:rc1:*:*:*:*:*:* | 6.13 rc1 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:6.13:rc2:*:*:*:*:*:* | 6.13 rc2 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:6.13:rc3:*:*:*:*:*:* | 6.13 rc3 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:6.13:rc4:*:*:*:*:*:* | 6.13 rc4 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:6.13:rc5:*:*:*:*:*:* | 6.13 rc5 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:6.13:rc6:*:*:*:*:*:* | 6.13 rc6 | Vulnerable | Linux |
- cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions 6.1 to before 6.1.125; 6.2 to before 6.6.72; 6.7 to before 6.12.10 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:6.13:rc1:*:*:*:*:*:* Versions 6.13 rc1 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:6.13:rc2:*:*:*:*:*:* Versions 6.13 rc2 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:6.13:rc3:*:*:*:*:*:* Versions 6.13 rc3 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:6.13:rc4:*:*:*:*:*:* Versions 6.13 rc4 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:6.13:rc5:*:*:*:*:*:* Versions 6.13 rc5 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:6.13:rc6:*:*:*:*:*:* Versions 6.13 rc6 Vulnerable ·Linux
Remediation
- Fix · CNA Linux (Linux) Fixed in 6.1.125, 6.6.72, 6.12.10, 6.13
Red Hat 1 advisory
- RHSA-2025:20095 Released 2025-11-11 · Red Hat rating Moderatekernel security update
- Red Hat Enterprise Linux AppStream (v. 10) kernel-64k-debug-devel-6.12.0-124.8.1.el10_1, kernel-64k-debug-devel-matched-6.12.0-124.8.1.el10_1, kernel-64k-devel-6.12.0-124.8.1.el10_1 +12
- Red Hat Enterprise Linux BaseOS (v. 10) kernel-6.12.0-124.8.1.el10_1, kernel-64k-6.12.0-124.8.1.el10_1, kernel-64k-core-6.12.0-124.8.1.el10_1 +29
- Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) kernel-tools-libs-devel-6.12.0-124.8.1.el10_1, libperf-6.12.0-124.8.1.el10_1
- Red Hat Enterprise Linux Real Time (v. 10) kernel-rt-6.12.0-124.8.1.el10_1, kernel-rt-64k-6.12.0-124.8.1.el10_1, kernel-rt-64k-core-6.12.0-124.8.1.el10_1 +21
- Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt-6.12.0-124.8.1.el10_1, kernel-rt-core-6.12.0-124.8.1.el10_1, kernel-rt-debug-6.12.0-124.8.1.el10_1 +9
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux AppStream (v. 10) | Fixed | RHSA-2025:20095 |
| Red Hat Enterprise Linux BaseOS (v. 10) | Fixed | RHSA-2025:20095 |
| Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) | Fixed | RHSA-2025:20095 |
| Red Hat Enterprise Linux Real Time (v. 10) | Fixed | RHSA-2025:20095 |
| Red Hat Enterprise Linux Real Time for NFV (v. 10) | Fixed | RHSA-2025:20095 |
Not affected: 4 products
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
Timeline
- 2026-10-02 Threatist record created from CVE-2025-21655
- 2026-10-03 Alias added: GHSA-vwm2-fvjj-vcv3
References
Patch 4
More Linux Kernel vulnerabilities
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- TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
- TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
- TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
- TI-2021-05514 Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACE KEVCVSS 3.1HIGH 8.3
Sources
- CVE-2025-21655 · CVE Program
- CVE-2025-21655 · NVD
- FIRST EPSS
- GHSA-vwm2-fvjj-vcv3 · GitHub Advisory Database · CC BY 4.0
- CVE-2025-21655 · Red Hat security data · CC BY 4.0
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