ip6: vti: Use ip6_tnl.net in vti6_siocdevprivate().
In the Linux kernel, the following vulnerability has been resolved: ip6: vti: Use ip6_tnl.net in vti6_siocdevprivate(). After patch 1/2 in this series, vti6_update() unlinks and relinks the tunnel through t->net. vti6_siocdevprivate() still uses dev_net(dev) for the collision lookup. For a tunnel moved through IFLA_NET_NS_FD, dev_net(dev) is the new netns, not t->net. SIOCCHGTUNNEL on a migrated tunnel then runs: net = dev_net(dev) /* migrated netns */ t = vti6_locate(net, &p1, false) /* misses target in t->net */ ... t = netdev_priv(dev) vti6_update(t, &p1, false) /* mutates t->net's hash */ A caller in the migrated netns picks params that match a tunnel in the creation netns. The lookup in dev_net(dev) finds nothing. vti6_update() prepends the migrated tunnel at the head of the creation netns hash bucket for those params. Later lookups in the creation netns resolve to the migrated device. xfrm receive delivers the matched packets through a device the caller controls. Reachable from an unprivileged user namespace (unshare --user --map-root-user --net). Cross tenant scope on container hosts. Switch the SIOCCHGTUNNEL path on a non fallback device to use t->net for the lookup. The lookup now matches the netns vti6_update() operates on. Also add ns_capable(self->net->user_ns, CAP_NET_ADMIN) before the lookup. The check at the top of the case is against dev_net(dev)->user_ns, which after migration is the attacker's netns. A caller there can pick params absent from self->net, the
CVE-2026-63921
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-63921
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "61220ab349485d911083d0b7990ccd3db6c63297",
"lessThan": "94ff740a7f9ef5c010784a325dca00cbf228f941",
"versionType": "git"
},
{
"status": "affected",
"version": "61220ab349485d911083d0b7990ccd3db6c63297",
"lessThan": "df42ac708acc3399bbb6dc5ca16e0540adda7bbf",
"versionType": "git"
},
{
"status": "affected",
"version": "61220ab349485d911083d0b7990ccd3db6c63297",
"lessThan": "44d2ff7d2178503b93151140a45dfa2ad49c9906",
"versionType": "git"
},
{
"status": "affected",
"version": "61220ab349485d911083d0b7990ccd3db6c63297",
"lessThan": "1acfb7d9c6fc7e209ed7789392697e97e03edd33",
"versionType": "git"
},
{
"status": "affected",
"version": "61220ab349485d911083d0b7990ccd3db6c63297",
"lessThan": "d2236348414bdd6558385f35aa7fdc9bf5634011",
"versionType": "git"
},
{
"status": "affected",
"version": "61220ab349485d911083d0b7990ccd3db6c63297",
"lessThan": "853f6ea482dfcd3404bbef458ab4d68364eed838",
"versionType": "git"
},
{
"status": "affected",
"version": "61220ab349485d911083d0b7990ccd3db6c63297",
"lessThan": "596f6354c96a891e58c04a09cbfb7b0d1ec00dab",
"versionType": "git"
},
{
"status": "affected",
"version": "61220ab349485d911083d0b7990ccd3db6c63297",
"lessThan": "8b484efd5cb4eeef9021a661e198edc5349dacf6",
"versionType": "git"
}
],
"programFiles": [
"net/ipv6/ip6_vti.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "3.15"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "3.15",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.10.259",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.210",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.176",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.143",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.93",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.35",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.0.12",
"versionType": "semver",
"lessThanOrEqual": "7.0.*"
},
{
"status": "unaffected",
"version": "7.1",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/ipv6/ip6_vti.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-63921
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #40894 · Revision 1
- Added to Heist Feed
- Publisher date