{
  "threat_severity" : "Moderate",
  "public_date" : "2026-07-25T00:00:00Z",
  "bugzilla" : {
    "description" : "kernel: mm: shrinker: fix shrinker_info teardown race with expansion",
    "id" : "2507285",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2507285"
  },
  "cvss3" : {
    "cvss3_base_score" : "7.0",
    "cvss3_scoring_vector" : "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H",
    "status" : "verified"
  },
  "cwe" : "CWE-364",
  "details" : [ "In the Linux kernel, the following vulnerability has been resolved:\nmm: shrinker: fix shrinker_info teardown race with expansion\nexpand_shrinker_info() iterates all visible memcgs under shrinker_mutex,\nincluding memcgs that have not finished ->css_online() yet.\nOnce pn->shrinker_info has been published, teardown must stay serialized\nwith expand_shrinker_info() until that memcg is either fully online or no\nlonger visible to iteration.  Today alloc_shrinker_info() breaks that rule\nby dropping shrinker_mutex before freeing a partially initialized\nshrinker_info array, which may cause the following race:\nCPU0                   CPU1\n====                   ====\ncss_create\n--> list_add_tail_rcu(&css->sibling, &parent_css->children);\nonline_css\n--> mem_cgroup_css_online\n--> alloc_shrinker_info\n--> alloc node0 info\nrcu_assign_pointer(C->node0->shrinker_info, old0)\nalloc node1 info -> FAIL -> goto err\nmutex_unlock(shrinker_mutex)\nshrinker_alloc()\n--> shrinker_memcg_alloc\n--> mutex_lock(shrinker_mutex)\nexpand_shrinker_info\n--> mem_cgroup_iter see the memcg\nexpand_one_shrinker_info\n--> old0 = C->node0->shrinker_info\nmemcpy(new->unit, old0->unit, ...);\nfree_shrinker_info\n--> kvfree(old0);\n/* double free !! */\nkvfree_rcu(old0, rcu);\nThe same problem exists later in mem_cgroup_css_online().  If\nalloc_shrinker_info() succeeds but a subsequent objcg allocation fails,\nthe free_objcg -> free_shrinker_info() unwind path tears down the already\npublished pn->shrinker_info arrays without shrinker_mutex.  The\nexpand_one_shrinker_info() can race with that teardown in the same way,\nleading to use-after-free or double-free of the old shrinker_info.\nFix this by serializing shrinker_info teardown with shrinker_mutex, and by\nkeeping alloc_shrinker_info() error cleanup inside the locked section.", "A flaw was found in the Linux kernel's memory management (mm) shrinker subsystem. A race condition exists where the `shrinker_info` array can be prematurely freed while still accessible, leading to a use-after-free or double-free vulnerability. This memory corruption can be exploited by a local attacker to cause system instability or a denial of service." ],
  "affected_release" : [ {
    "product_name" : "Red Hat Enterprise Linux 10",
    "release_date" : "2026-09-01T00:00:00Z",
    "advisory" : "RHSA-2026:61887",
    "cpe" : "cpe:/o:redhat:enterprise_linux:10.2",
    "package" : "kernel-0:6.12.0-211.50.1.el10_2"
  } ],
  "package_state" : [ {
    "product_name" : "Red Hat Enterprise Linux 6",
    "fix_state" : "Not affected",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:6"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7",
    "fix_state" : "Not affected",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7",
    "fix_state" : "Not affected",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8",
    "fix_state" : "Not affected",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:8"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8",
    "fix_state" : "Not affected",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:8"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "fix_state" : "Not affected",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:9"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "fix_state" : "Not affected",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:9"
  } ],
  "references" : [ "https://www.cve.org/CVERecord?id=CVE-2026-64418\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-64418\nhttps://lore.kernel.org/linux-cve-announce/2026072533-CVE-2026-64418-4aed@gregkh/T" ],
  "name" : "CVE-2026-64418",
  "csaw" : false
}