{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "d3aedd5ebd4b0b925b0bcda548066803e1318499"
            },
            {
              "fixed": "4b6798024f7b2d535f3db1002c760143cdbd1bd3"
            },
            {
              "fixed": "3c54b66c83fb8fcbde8e6a7bf90b65856e39f827"
            },
            {
              "fixed": "5a6b15f861b7c1304949e3350d23490a5fe429fd"
            },
            {
              "fixed": "6c7fbdb8ffde6413640de7cfbd7c976c353e89f8"
            },
            {
              "fixed": "8027964931785cb73d520ac70a342a3dc16c249b"
            },
            {
              "fixed": "414726b69921fe6355ae453f5b35e68dd078342a"
            },
            {
              "fixed": "572ce62778519a7d4d1c15f55dd2e45a474133c4"
            },
            {
              "fixed": "9ca562bb8e66978b53028fa32b1a190708e6a091"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.9.0"
            },
            {
              "fixed": "5.10.253"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.11.0"
            },
            {
              "fixed": "5.15.203"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.16.0"
            },
            {
              "fixed": "6.1.168"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.2.0"
            },
            {
              "fixed": "6.6.134"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.7.0"
            },
            {
              "fixed": "6.12.81"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.22"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "6.19.12"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31680.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ipv6: flowlabel: defer exclusive option free until RCU teardown\n\n`ip6fl_seq_show()` walks the global flowlabel hash under the seq-file\nRCU read-side lock and prints `fl-\u003eopt-\u003eopt_nflen` when an option block\nis present.\n\nExclusive flowlabels currently free `fl-\u003eopt` as soon as `fl-\u003eusers`\ndrops to zero in `fl_release()`. However, the surrounding\n`struct ip6_flowlabel` remains visible in the global hash table until\nlater garbage collection removes it and `fl_free_rcu()` finally tears it\ndown.\n\nA concurrent `/proc/net/ip6_flowlabel` reader can therefore race that\nearly `kfree()` and dereference freed option state, triggering a crash\nin `ip6fl_seq_show()`.\n\nFix this by keeping `fl-\u003eopt` alive until `fl_free_rcu()`. That matches\nthe lifetime already required for the enclosing flowlabel while readers\ncan still reach it under RCU.",
  "id": "CVE-2026-31680",
  "modified": "2026-07-08T05:36:51.772820536Z",
  "published": "2026-04-25T08:46:56.807Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3c54b66c83fb8fcbde8e6a7bf90b65856e39f827"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/414726b69921fe6355ae453f5b35e68dd078342a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4b6798024f7b2d535f3db1002c760143cdbd1bd3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/572ce62778519a7d4d1c15f55dd2e45a474133c4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5a6b15f861b7c1304949e3350d23490a5fe429fd"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6c7fbdb8ffde6413640de7cfbd7c976c353e89f8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8027964931785cb73d520ac70a342a3dc16c249b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9ca562bb8e66978b53028fa32b1a190708e6a091"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31680.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31680"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.7.5",
  "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: ipv6: flowlabel: defer exclusive option free until RCU teardown"
}