CVE-2025-21655io_uring/eventfd: ensure io_eventfd_signal() defers another RCU period
- 7.8HighCVSS base score
- 0.25%Exploitation in 30 daysEPSS · top 83% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
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.
Timeline
ID reserved
By Linux
- 22 days later
· 22 days later
Published
- 22 months later
· 22 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| LinuxCNA (assigner) | 3.1 | High7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| NVDNVD · Modified | 3.1 | Medium4.7 | CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.25% · top 83% of all CVEs (12 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.8.
Affected products
- affected 21a091b970cdbcf3e8ff829234b51be6f9192766 – < 6b63308c28987c6010b1180c72a6db4df6c68033
- affected 21a091b970cdbcf3e8ff829234b51be6f9192766 – < 8efff2aa2d95dc437ab67c5b4a9f1d3f367baa10
- affected 21a091b970cdbcf3e8ff829234b51be6f9192766 – < a7085c3ae43b86d4b3d1b8275e6a67f14257e3b7
- affected 21a091b970cdbcf3e8ff829234b51be6f9192766 – < c9a40292a44e78f71258b8522655bffaf5753bdb
- affected 6.1
- unaffected < 6.1
- unaffected 6.1.125 – ≤ 6.1.*
- unaffected 6.6.72 – ≤ 6.6.*
- unaffected 6.12.10 – ≤ 6.12.*
- unaffected 6.13 – ≤ *
References
References8
- https://git.kernel.org/stable/c/6b63308c28987c6010b1180c72a6db4df6c68033 (opens in a new tab)
- https://git.kernel.org/stable/c/8efff2aa2d95dc437ab67c5b4a9f1d3f367baa10 (opens in a new tab)
- https://git.kernel.org/stable/c/a7085c3ae43b86d4b3d1b8275e6a67f14257e3b7 (opens in a new tab)
- https://git.kernel.org/stable/c/c9a40292a44e78f71258b8522655bffaf5753bdb (opens in a new tab)
- https://project-zero.issues.chromium.org/issues/388499293 (opens in a new tab)
- https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html (opens in a new tab)
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html (opens in a new tab)
- https://cert-portal.siemens.com/productcert/html/ssa-457936.html (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2025-2604 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2025-21655)Record last updated .