{
  "schemaVersion": 1,
  "attribution": [
    {
      "source": "CISA Known Exploited Vulnerabilities",
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog",
      "licence": "US government work"
    },
    {
      "source": "GitHub Advisory Database",
      "url": "https://github.com/advisories",
      "licence": "CC BY 4.0"
    },
    {
      "source": "Have I Been Pwned",
      "url": "https://haveibeenpwned.com/",
      "licence": "CC BY 4.0"
    },
    {
      "source": "CVE Program (CVE records)",
      "url": "https://www.cve.org/Legal/TermsOfUse",
      "licence": "CVE Terms of Use",
      "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.",
      "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy."
    },
    {
      "source": "FIRST EPSS",
      "url": "https://www.first.org/epss/",
      "licence": "free to use; FIRST requests attribution"
    }
  ],
  "record": {
    "id": "CVE-2026-89791",
    "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-89791",
    "idYear": 2026,
    "status": "PUBLISHED",
    "publishedAt": "2026-09-16T08:48:27.020Z",
    "updatedAt": "2026-10-19T08:52:45.122Z",
    "importedAt": "2026-10-24T01:58:35.090Z",
    "snapshot": {
      "id": "cve_2026-10-24_midnight_baseline",
      "at": "2026-10-24T00:00:00.000Z",
      "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z"
    },
    "facts": {
      "title": "perf: Fix use-after-free when perf mmap() revival races with the last munmap()",
      "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\nperf: Fix use-after-free when perf mmap() revival races with the last munmap()\n\nperf_mmap_close() drops rb->mmap_count *without* holding\nevent->mmap_mutex (the refcount_dec_and_test() right before the\nrefcount_dec_and_mutex_lock() of event->mmap_count). A concurrent\nperf_mmap_rb() can slot its entire \"revival\" path into that window\n(perf_mmap holds event->mmap_mutex for its whole duration, including\nrb_alloc):\n\n  munmap side (perf_mmap_close)          mmap side (perf_mmap_rb)\n  -----------------------------------    --------------------------------\n  rb->mmap_count 1 -> 0   (no lock)      (holds event->mmap_mutex)\n                                         inc_not_zero(rb->mmap_count) fails\n                                         ring_buffer_attach(event, NULL)\n                                         rb_alloc() + attach new rb\n                                         refcount_set(&event->mmap_count, 1)\n  lock; event->mmap_count 1 -> 0\n  ring_buffer_attach(event, NULL)\n  ring_buffer_put() -> frees the *new* rb\n\nThe revival's refcount_set(&event->mmap_count, 1) is an invisible\n1 -> 1 write: the close frees the just-revived buffer although the\nother process still has it mapped -- a page-level use-after-free\nallowing local privilege escalation to root by any unprivileged user\n(default kernel.perf_event_paranoid=2).\n\nSwap the order of the two counter updates: event->mmap_count is\ndropped first via refcount_dec_and_mutex_lock(), so its 1 -> 0\ntransition and the ring_buffer_attach() stay serialized with\nperf_mmap(). rb->mmap_count == 0 then implies every event using the\nbuffer is detached already, so the result of the rb->mmap_count drop\ncan gate the remaining teardown directly and detach_rest is no longer\nneeded.\n\nAn earlier fix for this race from Kyle Zeng and David Lee takes\nevent->mmap_mutex around both counter updates [0]; here the not-last\nclose stays lockless.",
      "affected": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "59741451b49ce9964a9758c19d6f7df2a1255c75",
              "status": "affected",
              "versionType": "git",
              "lessThan": "929cb3b9dc818dd9fa89d510d4ff2b255e42badd"
            },
            {
              "version": "59741451b49ce9964a9758c19d6f7df2a1255c75",
              "status": "affected",
              "versionType": "git",
              "lessThan": "0c739f54f1c77f3a4643160cd2e031b6c2f2aab6"
            },
            {
              "version": "59741451b49ce9964a9758c19d6f7df2a1255c75",
              "status": "affected",
              "versionType": "git",
              "lessThan": "58a8108bc73de0740d5b88150465d6690ea5f85f"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "versions": [
            {
              "version": "6.18",
              "status": "affected"
            },
            {
              "version": "0",
              "status": "unaffected",
              "versionType": "semver",
              "lessThan": "6.18"
            },
            {
              "version": "6.18.52",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "version": "7.2.5",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "7.2.*"
            },
            {
              "version": "7.3",
              "status": "unaffected",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ]
        }
      ]
    }
  }
}