{
  "cveId": "CVE-2026-23127",
  "url": "https://patchblox.com/security/cve/CVE-2026-23127",
  "summary": "CVE-2026-23127 is fixed in linux on 1 platform by DEBIAN-CVE-2026-23127 (version 6.18.8-1), released February 14, 2026. It is not reported as exploited. Patch Radar priority: Routine.",
  "title": "linux: In the Linux kernel, the following vulnerability has been resolved:  perf: Fix refcount warning on event-\u003Emmap_count...",
  "description": "In the Linux kernel, the following vulnerability has been resolved:  perf: Fix refcount warning on event-\u003Emmap_count increment  When calling refcount_inc(\u0026event-\u003Emmap_count) inside perf_mmap_rb(), the following warning is triggered:          refcount_t: addition on 0; use-after-free.         WARNING: lib/refcount.c:25  PoC:      struct perf_event_attr attr = {0};     int fd = syscall(__NR_perf_event_open, \u0026attr, 0, -1, -1, 0);     mmap(NULL, 0x3000, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);     int victim = syscall(__NR_perf_event_open, \u0026attr, 0, -1, fd,                          PERF_FLAG_FD_OUTPUT);     mmap(NULL, 0x3000, PROT_READ | PROT_WRITE, MAP_SHARED, victim, 0);  This occurs when creating a group member event with the flag PERF_FLAG_FD_OUTPUT. The group leader should be mmap-ed and then mmap-ing the event triggers the warning.  Since the event has copied the output_event in perf_event_set_output(), event-\u003Erb is set. As a result, perf_mmap_rb() calls refcount_inc(\u0026event-\u003Emmap_count) when event-\u003Emmap_count = 0.  Disallow the case when event-\u003Emmap_count = 0. This also prevents two events from updating the same user_page.",
  "published": "2026-02-14T15:16:07Z",
  "severity": "medium",
  "cvss": 5.5,
  "cvssVector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
  "epss": 0.00117,
  "epssPercentile": 0.01683,
  "priority": "Routine",
  "priorityTier": 4,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 14",
      "fixedVersion": "6.18.8-1",
      "fix": "DEBIAN-CVE-2026-23127",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-23127",
      "released": "2026-02-14T15:16:07Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-09T01:18:40Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}