{"id":"CVE-2026-63802","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nblk-cgroup: fix UAF in __blkcg_rstat_flush()\n\nWhen multiple blkgs in the same blkcg are released concurrently,\na use-after-free can occur","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nblk-cgroup: fix UAF in __blkcg_rstat_flush()\n\nWhen multiple blkgs in the same blkcg are released concurrently,\na use-after-free can occur. The race happens when one blk…","severity":"high","published":"2026-07-19","updated":"2026-07-19","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-63802","references":[{"url":"https://git.kernel.org/stable/c/0ab5ee5a1badb58cbb2242617cb01a4972b1f2a2","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/5e5b7f2ef854936e95dceb6a2fdfefcb7152d2c6","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/96e545410c4f74c89d496c1d5d9ef8d08f14368b","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/afebe44facc48a61761e885bbb7f0380d4a603ec","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/bbebd9425cad3573d1527441753899b926525a0f","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63802.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-63802"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2502251"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-63802"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-63802"},{"url":"https://lore.kernel.org/linux-cve-announce/2026071901-CVE-2026-63802-1c53@gregkh/T"},{"url":"https://access.redhat.com/errata/RHSA-2026:67468"},{"url":"https://access.redhat.com/errata/RHSA-2026:67469"}],"tags":["nvd","csaf","vex","red-hat"],"ingestedAt":"2026-07-20T01:35:22.919Z","epss":0.00132,"epssPercentile":0.03145,"vendor":"Red Hat","product":"Red Hat Enterprise Linux 9","affected":["enterprise_linux 10","enterprise_linux 6","enterprise_linux 9","enterprise_linux_baseos_v_8","enterprise_linux_crb_v_8","enterprise_linux_nfv_v_8","enterprise_linux_rt_v_8"],"patched":["enterprise_linux_baseos_v_8","enterprise_linux_crb_v_8","enterprise_linux_nfv_v_8","enterprise_linux_rt_v_8"],"cvss":7,"cvssVector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","cvssSource":"vendor","cwe":["CWE-825"],"slug":"CVE-2026-63802","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nblk-cgroup: fix UAF in __blkcg_rstat_flush()\n\nWhen multiple blkgs in the same blkcg are released concurrently,\na use-after-free can occur. The race happens when one blkg's\n__blkcg_rstat_flush() removes another blkg's iostat entries via\nllist_del_all(). The second blkg sees an empty list and proceeds\nto free itself while the first is still iterating over its entries.\n\nMove the flush from __blkg_release() (RCU callback) to blkg_release()\n(before call_rcu). This ensures the RCU grace period waits for any\nconcurrent flush's rcu_read_lock() section to complete before freeing.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **RHSA-2026:67468** · Red Hat · fixed in: Red Hat Enterprise Linux BaseOS (v. 8), Red Hat Enterprise Linux CRB (v. 8) · released 2026-09-15 · [advisory](https://access.redhat.com/errata/RHSA-2026:67468)\n- **RHSA-2026:67469** · Red Hat · fixed in: Red Hat Enterprise Linux NFV (v. 8), Red Hat Enterprise Linux RT (v. 8) · released 2026-09-15 · [advisory](https://access.redhat.com/errata/RHSA-2026:67469)\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9 · updated 2026-09-15 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63802.json)","depth":"twilight","depthScore":39,"depthScoreParts":{"impact":38.5,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":203976,"id":"CVE-2026-63802","ts":1789490230877,"field":"cvss","old":null,"new":"7"},{"seq":203975,"id":"CVE-2026-63802","ts":1789490230877,"field":"severity","old":"none","new":"high"}]}