{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "882ba1f73c06831f2a21044ebd8864c485ac04f2"
            },
            {
              "fixed": "2c2091e2ee93049fc513ad1e6c99d8b6c809f467"
            },
            {
              "fixed": "20db91a052332ef5552bd2f651ffb9db911cf67b"
            },
            {
              "fixed": "c073d1b070f171d206b19c98d71739a97f15b3f1"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        },
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "47c75e3923c8d562fea8daf0ccf31546a7bef0ea"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        },
        {
          "events": [
            {
              "introduced": "5.10.261"
            },
            {
              "fixed": "5.11"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.13.0"
            },
            {
              "fixed": "6.18.53"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.2.7"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98101.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: mcast: use copy-on-write RCU updates in ip6_mc_source()\n\npmc-\u003esflist is read locklessly under rcu_read_lock() by\ninet6_mc_check() during packet reception in the UDP and RAW\nmulticast receive paths.\n\nip6_mc_source() mutated psl-\u003esl_addr and psl-\u003esl_count in-place\nwhen adding or removing a source filter. Additionally, when expanding\nthe filter buffer, newpsl was published via rcu_assign_pointer()\nbefore writing the new source into the array.\n\nBecause 16-byte struct in6_addr writes are not atomic and array\nshifting is not synchronized with RCU readers, concurrent readers in\ninet6_mc_check() could read torn IPv6 addresses or observe\nduplicated/missed source entries.\n\nFix this by switching ip6_mc_source() to copy-on-write RCU updates:\nallocate and fully populate newpsl before publishing it via\nrcu_assign_pointer(), and reclaim the old filter via kfree_rcu(),\nmatching ip6_mc_msfilter().\n\nAlso remove the now unused IP6_SFBLOCK macro.",
  "id": "CVE-2026-98101",
  "modified": "2026-09-27T03:30:30.961534167Z",
  "published": "2026-09-25T10:35:52.731Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/20db91a052332ef5552bd2f651ffb9db911cf67b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2c2091e2ee93049fc513ad1e6c99d8b6c809f467"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c073d1b070f171d206b19c98d71739a97f15b3f1"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98101.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98101"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.9.0",
  "summary": "ipv6: mcast: use copy-on-write RCU updates in ip6_mc_source()"
}