{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "720f22fed81bc6fd1765db7014651b6718887bea"
            },
            {
              "fixed": "5f038affdacaffedf6a85a06cf59ec0a852d36a7"
            },
            {
              "fixed": "efa58aeb6a99028b1fbc3ab2f31ba3a881211ad4"
            },
            {
              "fixed": "725efc2ab4a40affc4e285a2dc4896d103948a6c"
            },
            {
              "fixed": "6bcb8839aa2d686964a4154650afc4db91e1c514"
            },
            {
              "fixed": "5344e01179baa37547ab29fd7b8614f83faa190c"
            },
            {
              "fixed": "92f00f1d4d204a428b38e26fce3baee144b6955d"
            },
            {
              "fixed": "2e8df8c9190335475a3b64a159d3efd8cdd1cb73"
            },
            {
              "fixed": "883b56ae58fe657d8497806c7059646e9ba6dbd0"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.3.0"
            },
            {
              "fixed": "5.10.266"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.11.0"
            },
            {
              "fixed": "5.15.216"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.16.0"
            },
            {
              "fixed": "6.1.183"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.2.0"
            },
            {
              "fixed": "6.6.152"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.7.0"
            },
            {
              "fixed": "6.12.104"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.45"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.1.9"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74620.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: act_gact, act_police: range check the fallback control action\n\ntcf_action_check_ctrlact() range checks the primary control action:\n\n\tif (!opcode)\n\t\tret = action \u003e TC_ACT_VALUE_MAX ? -EINVAL : 0;\n\nTC_ACT_VALUE_MAX is TC_ACT_TRAP, so kernel-internal verdicts above it\ncannot be set that way. But act_gact and act_police each carry a second,\nindependent control action supplied by user space that never reaches that\nhelper - TCA_GACT_PROB.paction and TCA_POLICE_RESULT. Both only reject\nTC_ACT_GOTO_CHAIN, so any other value is stored verbatim and returned\nverbatim from the action.\n\nIn particular user space can store TC_ACT_CONSUMED, which is\nTC_ACT_VALUE_MAX + 1 and is deliberately not part of the UAPI value\nrange. That verdict tells every caller the action took ownership of the\nskb, so nobody frees it: sch_handle_ingress(), sch_handle_egress() and\ntcf_qevent_handle() all deliberately skip the free for it. The result is\none leaked sk_buff plus its data buffer per packet traversing the filter,\nunbounded, for all traffic on the chain including kernel-generated\npackets.\n\nBoth are trivially deterministic. act_gact clamps tcfg_pval to \u003e= 1, so\nwith pval = 1 gact_determ() returns the fallback for every packet.\nact_police has no mandatory rate, so rate = 0 leaves tcfp_mtu = ~0 and\ntcf_police_mtu_check() always passes.\n\nTC_ACT_CONSUMED was added by commit 720f22fed81b (\"net: sched: refactor\nreinsert action\"), after both goto-chain guards were written:\ncommit 9469f375ab09 (\"net/sched: act_gact: disallow 'goto chain' on\nfallback control action\") and\ncommit c08f5ed5d625 (\"net/sched: act_police: disallow 'goto chain' on\nfallback control action\"). Neither guard was widened when the new\nverdict appeared.\n\nFactor the existing range test out of tcf_action_check_ctrlact() as\ntcf_action_valid() and apply it to both fallbacks. The helper cannot call\ntcf_action_check_ctrlact() directly because that also allocates a\ngoto_chain, which is exactly what these two sites must not do.\n\nReproduced on v7.2-rc6: kmemleak reports one leaked 232-byte\nskbuff_head_cache object plus its 704-byte data buffer per packet. With\nthis patch both configurations are rejected with -EINVAL and kmemleak\nreports none.",
  "id": "CVE-2026-74620",
  "modified": "2026-08-25T03:51:34.932508078Z",
  "published": "2026-08-22T15:32:04.254Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2e8df8c9190335475a3b64a159d3efd8cdd1cb73"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5344e01179baa37547ab29fd7b8614f83faa190c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5f038affdacaffedf6a85a06cf59ec0a852d36a7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6bcb8839aa2d686964a4154650afc4db91e1c514"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/725efc2ab4a40affc4e285a2dc4896d103948a6c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/883b56ae58fe657d8497806c7059646e9ba6dbd0"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/92f00f1d4d204a428b38e26fce3baee144b6955d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/efa58aeb6a99028b1fbc3ab2f31ba3a881211ad4"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74620.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-74620"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.9.0",
  "summary": "net/sched: act_gact, act_police: range check the fallback control action"
}