CVE-2025-21655io_uring/eventfd: ensure io_eventfd_signal() defers another RCU period
Updated under an hour ago ()
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It affects Linux and 4 other products. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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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.
- CVSS
- 7.8 HIGH (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Modified
- Record last updated
- Oct 15, 2026
- First seen by InfoSec Signals
- Oct 15, 2026
Affected products
Linux Linux linux:linux (from the name) | 21a091b970cdbcf3e8ff829234b51be6f9192766 builds before 6b63308c28987c6010b1180c72a6db4df6c68033; 21a091b970cdbcf3e8ff829234b51be6f9192766 builds before 8efff2aa2d95dc437ab67c5b4a9f1d3f367baa10; from 21a091b970cdbcf3e8ff829234b51be6f9192766 before a7085c3ae43b86d4b3d1b8275e6a67f14257e3b7; from 21a091b970cdbcf3e8ff829234b51be6f9192766 before c9a40292a44e78f71258b8522655bffaf5753bdb | CNA record |
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518_4_pn_dp_mfp (from the name) | from V3.1.6 | CISA ADP |
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518f_4_pn_dp_mfp (from the name) | from V3.1.6 | CISA ADP |
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP siemens:siplus_s7_1500_cpu_1518_4_pn_dp_mfp (from the name) | from V3.1.6 | CISA ADP |
linux linux_kernel linux:linux_kernel | from 6.1 before 6.1.125; from 6.2 before 6.6.72; from 6.7 before 6.12.10; 6.13; 6.13; 6.13; 6.13; 6.13; and 1 more ranges | NVD |
References
- https://git.kernel.org/stable/c/6b63308c28987c6010b1180c72a6db4df6c68033patch
- https://git.kernel.org/stable/c/8efff2aa2d95dc437ab67c5b4a9f1d3f367baa10patch
- https://git.kernel.org/stable/c/a7085c3ae43b86d4b3d1b8275e6a67f14257e3b7patch
- https://git.kernel.org/stable/c/c9a40292a44e78f71258b8522655bffaf5753bdbpatch
- https://project-zero.issues.chromium.org/issues/388499293issue-tracking, third-party-advisory
- https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html
- https://cert-portal.siemens.com/productcert/html/ssa-457936.html
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.