{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "1109c00547fc66df45b9ff923544be4c1e1bec13"
            },
            {
              "fixed": "7897198b26445b4009a057bda1986b94a99e5d5f"
            },
            {
              "fixed": "820f083c294ad6d319c02a7d43294f2ed2565139"
            },
            {
              "fixed": "5ec9001be6d0eb527251125632ec8fe88278897f"
            },
            {
              "fixed": "b969984b2bdc85d721ce4047cd270cd37ec705a2"
            },
            {
              "fixed": "a17f636c9330eac879822ce29f998e5abd1b72c1"
            },
            {
              "fixed": "0e7a8cf8895b06d07c7311f028eba16ad742b9bc"
            },
            {
              "fixed": "ae9aff87025219005a2d16b4fe83d6f24643e50d"
            },
            {
              "fixed": "47d7f7051253bdc02b1d245d87e38f16d31a74df"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.18.0"
            },
            {
              "fixed": "5.10.265"
            }
          ],
          "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-2026-74583.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: cls_route: fix fastmap use-after-free on filter\n\nThe route4 classifier maintains a 16-slot fastmap cache that stores raw\nstruct route4_filter pointers indexed by (id, iif). The reader\n(route4_classify) populates this cache via route4_set_fastmap() for every\nclassified packet that hits a filter. The writer (route4_delete,\nroute4_change) clears the cache via route4_reset_fastmap() before\nRCU-deferred kfree of the filter.\n\nThis creates a UAF race:\n 1. Reader walks the RCU-protected bucket chain, finds filter f\n 2. Writer unlinks f, calls route4_reset_fastmap(), then tcf_queue_work()\n 3. Reader calls route4_set_fastmap() and writes f into the cache\n    *after* the writer's reset, caching a pointer about to be freed\n 4. After the RCU grace period, kfree(f) executes\n 5. Next classified packet on the same (id, iif) tuple hits the stale\n    fastmap entry and reads f-\u003eres from freed memory\n\nReproduced with an mdelay(100) accelerator in route4_set_fastmap() and a\nconcurrent add/delete stress test (provided by both zdi and Santosh).\nBoth triggered KASAN slab-use-after-free reports in the route4 fastmap\npaths.\n\nFix:\nIntroduce a per-filter boolean dying flag to suppress stale fastmap\nrepublishing by in-flight readers.",
  "id": "CVE-2026-74583",
  "modified": "2026-08-27T11:30:35.963536187Z",
  "published": "2026-08-21T16:31:55.886Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0e7a8cf8895b06d07c7311f028eba16ad742b9bc"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/47d7f7051253bdc02b1d245d87e38f16d31a74df"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5ec9001be6d0eb527251125632ec8fe88278897f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7897198b26445b4009a057bda1986b94a99e5d5f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/820f083c294ad6d319c02a7d43294f2ed2565139"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a17f636c9330eac879822ce29f998e5abd1b72c1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ae9aff87025219005a2d16b4fe83d6f24643e50d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b969984b2bdc85d721ce4047cd270cd37ec705a2"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74583.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-74583"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "net/sched: cls_route: fix fastmap use-after-free on filter"
}