{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-63917", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T07:54:57.020Z", "datePublished": "2026-07-19T14:55:20.703Z", "dateUpdated": "2026-08-05T12:37:11.588Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:37:11.588Z" }, "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->net stays at the creation netns.\n\nvti6_changelink() and vti6_update() still use dev_net(dev) and\ndev_net(t->dev). 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": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H", "baseScore": 8.8, "baseSeverity": "HIGH" }, "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's 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." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/ipv6/ip6_vti.c" ], "versions": [ { "version": "61220ab349485d911083d0b7990ccd3db6c63297", "lessThan": "0cdce7618464f7fb06f461e8f4ad575cb1d570f4", "status": "affected", "versionType": "git" }, { "version": "61220ab349485d911083d0b7990ccd3db6c63297", "lessThan": "f5c68875e25f331e497ddfbe81e2d8163a87f136", "status": "affected", "versionType": "git" }, { "version": "61220ab349485d911083d0b7990ccd3db6c63297", "lessThan": "d9c5eecdb3c740e65038651db7c686b10d76d1bc", "status": "affected", "versionType": "git" }, { "version": "61220ab349485d911083d0b7990ccd3db6c63297", "lessThan": "f1e89a943ee574d0f2f16246eb3f2d7330fdeb03", "status": "affected", "versionType": "git" }, { "version": "61220ab349485d911083d0b7990ccd3db6c63297", "lessThan": "225b467e3b631f38be22e4b38062a1fed02fdd21", "status": "affected", "versionType": "git" }, { "version": "61220ab349485d911083d0b7990ccd3db6c63297", "lessThan": "fc32be9ac2788524c6b24efd681cce7a6e731a92", "status": "affected", "versionType": "git" }, { "version": "61220ab349485d911083d0b7990ccd3db6c63297", "lessThan": "ee1778ba0f5cb53be771f97017d01eb356c797bf", "status": "affected", "versionType": "git" }, { "version": "61220ab349485d911083d0b7990ccd3db6c63297", "lessThan": "11b326fb0a374f4654f9be22d0f0f7abd9f7d3fe", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/ipv6/ip6_vti.c" ], "versions": [ { "version": "3.15", "status": "affected" }, { "version": "0", "lessThan": "3.15", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.259", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.210", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.176", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.143", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.93", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.35", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0.12", "lessThanOrEqual": "7.0.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.15", "versionEndExcluding": "5.10.259" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.15", "versionEndExcluding": "5.15.210" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.15", "versionEndExcluding": "6.1.176" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.15", "versionEndExcluding": "6.6.143" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.15", "versionEndExcluding": "6.12.93" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.15", "versionEndExcluding": "6.18.35" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.15", "versionEndExcluding": "7.0.12" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.15", "versionEndExcluding": "7.1" } ] } ] } ], "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" } } } }