{
  "affected": [
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:11",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "5.10.259-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:12",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.1.176-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:13",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.12.94-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:14",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "7.0.13-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:11",
        "name": "linux-6.1"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.1.176-1~deb11u1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "details": "In the Linux kernel, the following vulnerability has been resolved:  net/sched: act_api: use RCU with deferred freeing for action lifecycle  When NEWTFILTER and DELFILTER are run concurrently it is possible to create a race with an associated action.  Let's illustrate with CPU0 running NEWTFILTER and CPU1 running DELFILTER:   0: mutex_lock() \u003c-- holds the idr lock  0: rcu_read_lock()  0: p = idr_find(idr, index) \u003c-- action p is valid (RCU protects IDR)  0: mutex_unlock() \u003c-- releases the idr lock  1: refcount_dec_and_mutex_lock() \u003c-- refcnt 1-\u003e0, mutex held  1: idr_remove(idr, index) \u003c-- Action removed from IDR  1: mutex_unlock() \u003c-- mutex released allowing us to delete the action  1: tcf_action_cleanup(p); kfree(p) \u003c-- Kfrees p immediately, no deferral  0: refcount_inc_not_zero(\u0026p-\u003etcfa_refcnt) \u003c-- ouch, UAF p points to freed memory  This patch fixes the race condition between NEWTFILTER and DELFILTER by adding struct rcu_head to tc_action used in the deferral and introducing a call_rcu() in the delete path to defer the final kfree().  Note: this is a revert of commit d7fb60b9cafb (\"net_sched: get rid of tcfa_rcu\") but also modernization/simplification to directly use kfree_rcu().  Let's illustrate the new restored code path:   0: rcu_read_lock()  1: refcount_dec_and_mutex_lock() \u003c-- refcnt 1-\u003e0, mutex held  1: idr_remove(idr, index)  1: mutex_unlock()  1: call_rcu(\u0026p-\u003etcfa_rcu, tcf_action_rcu_free) \u003c-- defer kfree after grace period  0: p = idr_find(idr, index)  0: refcount_inc_not_zero(\u0026p-\u003etcfa_refcnt) \u003c-- fails, refcnt already 0  1: rcu_read_unlock() \u003c-- release so freeing can run after grace period  After CPU1 calls idr_remove(), the object is no longer reachable through the IDR. CPU0's subsequent idr_find() will return NULL, and even if it still held a stale pointer, the immediate kfree() is now deferred until after the RCU grace period, so no UAF can occur.",
  "id": "DEBIAN-CVE-2026-53264",
  "modified": "2026-07-05T19:48:24.040122159Z",
  "published": "2026-06-25T09:16:44.400Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://security-tracker.debian.org/tracker/CVE-2026-53264"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "upstream": [
    "CVE-2026-53264"
  ]
}