{"id":"CVE-2025-21655","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/eventfd: ensure io_eventfd_signal() defers another RCU period\n\nio_eventfd_do_signal() is invoked from an RCU callback, but when\ndropping the reference to the i…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/eventfd: ensure io_eventfd_signal() defers another RCU period\n\nio_eventfd_do_signal() is invoked from an RCU callback, but when\ndropping the reference to the i…","severity":"medium","cvss":4.7,"cvssVector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-416"],"vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 6.1, < 6.1.125","linux_kernel >= 6.2, < 6.6.72","linux_kernel >= 6.7, < 6.12.10","linux_kernel = 6.13"],"patched":["linux_kernel 6.12.10"],"published":"2025-01-20","updated":"2026-07-14","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2025-21655","references":[{"url":"https://git.kernel.org/stable/c/6b63308c28987c6010b1180c72a6db4df6c68033","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/8efff2aa2d95dc437ab67c5b4a9f1d3f367baa10","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/a7085c3ae43b86d4b3d1b8275e6a67f14257e3b7","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/c9a40292a44e78f71258b8522655bffaf5753bdb","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://project-zero.issues.chromium.org/issues/388499293","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-019113.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"}],"tags":["nvd","cve.org"],"epss":0.00253,"epssPercentile":0.1489,"ingestedAt":"2026-07-14T13:36:54.904Z","slug":"CVE-2025-21655","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/eventfd: ensure io_eventfd_signal() defers another RCU period\n\nio_eventfd_do_signal() is invoked from an RCU callback, but when\ndropping the reference to the io_ev_fd, it calls io_eventfd_free()\ndirectly if the refcount drops to zero. This isn't correct, as any\npotential freeing of the io_ev_fd should be deferred another RCU grace\nperiod.\n\nJust call io_eventfd_put() rather than open-code the dec-and-test and\nfree, which will correctly defer it another RCU grace period.\n\n## Affected\n\n- `linux_kernel >= 6.1, < 6.1.125`\n- `linux_kernel >= 6.2, < 6.6.72`\n- `linux_kernel >= 6.7, < 6.12.10`\n- `linux_kernel = 6.13`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 6.12.10`","depth":"sunlit","depthScore":26,"depthScoreParts":{"impact":25.9,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}