{
  "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-2026-63951",
    "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-63951",
    "idYear": 2026,
    "status": "PUBLISHED",
    "publishedAt": "2026-07-19T14:55:44.105Z",
    "updatedAt": "2026-08-05T12:37:36.330Z",
    "importedAt": "2026-10-24T01:58:25.636Z",
    "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": "zram: fix use-after-free in zram_writeback_endio",
      "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\nzram: fix use-after-free in zram_writeback_endio\n\nA crash was observed in zram_writeback_endio due to a NULL pointer\ndereference in wake_up.  The root cause is a race condition between the\nbio completion handler (zram_writeback_endio) and the writeback task.\n\nIn zram_writeback_endio, wake_up() is called on &wb_ctl->done_wait after\nreleasing wb_ctl->done_lock.  This creates a race window where the\nwriteback task can see num_inflight become 0, return, and free wb_ctl\nbefore zram_writeback_endio calls wake_up().\n\nCPU 0 (zram_writeback_endio)     CPU 1 (writeback_store)\n============================     ============================\n                                 zram_writeback_slots\n                                   zram_submit_wb_request\n                                   zram_submit_wb_request\n                                   wait_event(wb_ctl->done_wait)\nspin_lock(&wb_ctl->done_lock);\nlist_add(&req->entry, &wb_ctl->done_reqs);\nspin_unlock(&wb_ctl->done_lock);\nwake_up(&wb_ctl->done_wait);\n                                   zram_complete_done_reqs\nspin_lock(&wb_ctl->done_lock);\nlist_add(&req->entry, &wb_ctl->done_reqs);\nspin_unlock(&wb_ctl->done_lock);\n                                   while (num_inflight) > 0)\n                                     spin_lock(&wb_ctl->done_lock);\n                                     list_del(&req->entry);\n                                     spin_unlock(&wb_ctl->done_lock);\n                                     // num_inflight becomes 0\n                                     atomic_dec(num_inflight);\n\n                                 // Leave zram_writeback_slots\n                                 // Free wb_ctl\n                                 release_wb_ctl(wb_ctl);\n// UAF crash!\nwake_up(&wb_ctl->done_wait);\n\nThis patch fixes this race by using RCU.  By protecting wb_ctl with\nrcu_read_lock() in zram_writeback_endio and using kfree_rcu() to free it,\nwe ensure that wb_ctl remains valid during the execution of\nzram_writeback_endio.",
      "affected": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "f405066a1f0db818270f49a5e96be329bcabde1e",
              "status": "affected",
              "versionType": "git",
              "lessThan": "ebe2cbefc86291fa7f386447a81995640df4e2fd"
            },
            {
              "version": "f405066a1f0db818270f49a5e96be329bcabde1e",
              "status": "affected",
              "versionType": "git",
              "lessThan": "bf62f69574b19720ae5fbbbcdf24a0c4e3e05e43"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "versions": [
            {
              "version": "6.19",
              "status": "affected"
            },
            {
              "version": "0",
              "status": "unaffected",
              "versionType": "semver",
              "lessThan": "6.19"
            },
            {
              "version": "7.0.12",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "7.0.*"
            },
            {
              "version": "7.1",
              "status": "unaffected",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ]
        }
      ]
    }
  }
}