CVE-2026-63917 (GCVE-0-2026-63917)
Vulnerability from cvelistv5
Published
2026-07-19 14:55
Modified
2026-08-05 12:37
Severity ?
8.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: ip6: vti: Use ip6_tnl.net in vti6_changelink(). ip netns add ns1 ip netns add ns2 ip -n ns1 link add vti6_test type vti6 remote ::1 local ::2 key 7 ip -n ns1 link set vti6_test netns ns2 ip -n ns2 link set vti6_test type vti6 remote ::3 local ::4 key 9 ip netns del ns2 ip netns del ns1 [ 132.495484] ------------[ cut here ]------------ [ 132.497609] kernel BUG at net/core/dev.c:12376! Commit 61220ab34948 ("vti6: Enable namespace changing") dropped NETIF_F_NETNS_LOCAL from vti6 devices. A vti6 tunnel can then move through IFLA_NET_NS_FD. After the move dev_net(dev) points at the new netns while t->net stays at the creation netns. vti6_changelink() and vti6_update() still use dev_net(dev) and dev_net(t->dev). They unlink from one per netns hash and relink into another. The creation netns is left with a stale entry. cleanup_net() of that netns later walks freed memory. Reachable from an unprivileged user namespace (unshare --user --map-root-user --net). Cross tenant scope on container hosts.
References
Impacted products
Vendor Product Version
Linux Linux Version: 61220ab349485d911083d0b7990ccd3db6c63297
Version: 61220ab349485d911083d0b7990ccd3db6c63297
Version: 61220ab349485d911083d0b7990ccd3db6c63297
Version: 61220ab349485d911083d0b7990ccd3db6c63297
Version: 61220ab349485d911083d0b7990ccd3db6c63297
Version: 61220ab349485d911083d0b7990ccd3db6c63297
Version: 61220ab349485d911083d0b7990ccd3db6c63297
Version: 61220ab349485d911083d0b7990ccd3db6c63297
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/ipv6/ip6_vti.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "0cdce7618464f7fb06f461e8f4ad575cb1d570f4",
              "status": "affected",
              "version": "61220ab349485d911083d0b7990ccd3db6c63297",
              "versionType": "git"
            },
            {
              "lessThan": "f5c68875e25f331e497ddfbe81e2d8163a87f136",
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              "version": "61220ab349485d911083d0b7990ccd3db6c63297",
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            {
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            },
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              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/ipv6/ip6_vti.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "3.15"
            },
            {
              "lessThan": "3.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.259",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.210",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.176",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.143",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.93",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.35",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.12",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.259",
                  "versionStartIncluding": "3.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.210",
                  "versionStartIncluding": "3.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.176",
                  "versionStartIncluding": "3.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.143",
                  "versionStartIncluding": "3.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.93",
                  "versionStartIncluding": "3.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.35",
                  "versionStartIncluding": "3.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0.12",
                  "versionStartIncluding": "3.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1",
                  "versionStartIncluding": "3.15",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nip6: vti: Use ip6_tnl.net in vti6_changelink().\n\nip netns add ns1\nip netns add ns2\nip -n ns1 link add vti6_test type vti6 remote ::1 local ::2 key 7\nip -n ns1 link set vti6_test netns ns2\nip -n ns2 link set vti6_test type vti6 remote ::3 local ::4 key 9\nip netns del ns2\nip netns del ns1\n[  132.495484] ------------[ cut here ]------------\n[  132.497609] kernel BUG at net/core/dev.c:12376!\n\nCommit 61220ab34948 (\"vti6: Enable namespace changing\") dropped\nNETIF_F_NETNS_LOCAL from vti6 devices. A vti6 tunnel can then\nmove through IFLA_NET_NS_FD. After the move dev_net(dev) points\nat the new netns while t-\u003enet stays at the creation netns.\n\nvti6_changelink() and vti6_update() still use dev_net(dev) and\ndev_net(t-\u003edev). They unlink from one per netns hash and relink\ninto another. The creation netns is left with a stale entry.\ncleanup_net() of that netns later walks freed memory.\n\nReachable from an unprivileged user namespace (unshare --user\n--map-root-user --net). Cross tenant scope on container hosts."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The bug is reached only through rtnetlink configuration (RTM_NEWLINK changelink and RTM_SETLINK netns move via `ip link`), not through remote packet handling on the vti6 tunnel itself.\nAC:L - Exploitation is a deterministic, attacker-controlled sequence (create vti6, move netns, changelink, delete netns) with no races or external victim state required.\nPR:L - The fix commit and rtnetlink path confirm reachability with CAP_NET_ADMIN inside an unprivileged user+network namespace (`unshare --user --map-root-user --net`), not init-namespace root.\nUI:N - No victim interaction is required; the attacker triggers the bug entirely through their own netlink operations.\nS:C - On container hosts, an unprivileged tenant can corrupt namespace teardown and panic the host kernel, impacting resources outside the attacker\u0027s security scope (other tenants and the host).\nC:H - The stale per-netns hash leaves `cleanup_net()`/`vti6_exit_rtnl_net()` walking freed `ip6_tnl` list nodes, constituting a use-after-free with arbitrary kernel memory read potential.\nI:H - Cross-netns hash corruption can leave dangling pointers and drive `unregister_netdevice_queue()` on already-freed devices (kernel BUG at net/core/dev.c:12376), enabling memory corruption exploitable for control-flow hijacking.\nA:H - The published reproducer reliably triggers a kernel BUG during namespace cleanup, causing host-wide denial of service via kernel panic/oops."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:37:11.588Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/0cdce7618464f7fb06f461e8f4ad575cb1d570f4"
        },
        {
          "url": "https://git.kernel.org/stable/c/f5c68875e25f331e497ddfbe81e2d8163a87f136"
        },
        {
          "url": "https://git.kernel.org/stable/c/d9c5eecdb3c740e65038651db7c686b10d76d1bc"
        },
        {
          "url": "https://git.kernel.org/stable/c/f1e89a943ee574d0f2f16246eb3f2d7330fdeb03"
        },
        {
          "url": "https://git.kernel.org/stable/c/225b467e3b631f38be22e4b38062a1fed02fdd21"
        },
        {
          "url": "https://git.kernel.org/stable/c/fc32be9ac2788524c6b24efd681cce7a6e731a92"
        },
        {
          "url": "https://git.kernel.org/stable/c/ee1778ba0f5cb53be771f97017d01eb356c797bf"
        },
        {
          "url": "https://git.kernel.org/stable/c/11b326fb0a374f4654f9be22d0f0f7abd9f7d3fe"
        }
      ],
      "title": "ip6: vti: Use ip6_tnl.net in vti6_changelink().",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-63917",
    "datePublished": "2026-07-19T14:55:20.703Z",
    "dateReserved": "2026-07-19T07:54:57.020Z",
    "dateUpdated": "2026-08-05T12:37:11.588Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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