Answer in brief
CVE-2026-63921 records a Unknown severity vulnerability in ip6: vti: Use ip6_tnl.net in vti6_siocdevprivate().. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
Answer in brief
CVE-2026-63921 records a Unknown severity vulnerability in ip6: vti: Use ip6_tnl.net in vti6_siocdevprivate().. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=61220ab349485d911083d0b7990ccd3db6c63297 <94ff740a7f9ef5c010784a325dca00cbf228f941 || >=61220ab349485d911083d0b7990ccd3db6c63297 <df42ac708acc3399bbb6dc5ca16e0540adda7bbf || >=61220ab349485d911083d0b7990ccd3db6c63297 <44d2ff7d2178503b93151140a45dfa2ad49c9906 || >=61220ab349485d911083d0b7990ccd3db6c63297 <1acfb7d9c6fc7e209ed7789392697e97e03edd33 || >=61220ab349485d911083d0b7990ccd3db6c63297 <d2236348414bdd6558385f35aa7fdc9bf5634011 || >=61220ab349485d911083d0b7990ccd3db6c63297 <853f6ea482dfcd3404bbef458ab4d68364eed838 || >=61220ab349485d911083d0b7990ccd3db6c63297 <596f6354c96a891e58c04a09cbfb7b0d1ec00dab || >=61220ab349485d911083d0b7990ccd3db6c63297 <8b484efd5cb4eeef9021a661e198edc5349dacf6 | 94ff740a7f9ef5c010784a325dca00cbf228f941, df42ac708acc3399bbb6dc5ca16e0540adda7bbf, 44d2ff7d2178503b93151140a45dfa2ad49c9906, 1acfb7d9c6fc7e209ed7789392697e97e03edd33, d2236348414bdd6558385f35aa7fdc9bf5634011, 853f6ea482dfcd3404bbef458ab4d68364eed838, 596f6354c96a891e58c04a09cbfb7b0d1ec00dab, 8b484efd5cb4eeef9021a661e198edc5349dacf6 |
| Linux/Linuxgeneric | 3.15 | Not reported |
Published upstream
Jul 19, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 5, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 5, 2026
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 lookup returns NULL, t becomes self, and vti6_update() inserts the device into the creation netns hash. The new check requires CAP_NET_ADMIN in the creation netns user_ns too. SIOCADDTUNNEL and SIOCCHGTUNNEL on the fallback device keep dev_net(dev), which equals init_net there.
Quoted source text, attributed separately from HOL analysis.
A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=61220ab349485d911083d0b7990ccd3db6c63297 <94ff740a7f9ef5c010784a325dca00cbf228f941 || >=61220ab349485d911083d0b7990ccd3db6c63297 <df42ac708acc3399bbb6dc5ca16e0540adda7bbf || >=61220ab349485d911083d0b7990ccd3db6c63297 <44d2ff7d2178503b93151140a45dfa2ad49c9906 || >=61220ab349485d911083d0b7990ccd3db6c63297 <1acfb7d9c6fc7e209ed7789392697e97e03edd33 || >=61220ab349485d911083d0b7990ccd3db6c63297 <d2236348414bdd6558385f35aa7fdc9bf5634011 || >=61220ab349485d911083d0b7990ccd3db6c63297 <853f6ea482dfcd3404bbef458ab4d68364eed838 || >=61220ab349485d911083d0b7990ccd3db6c63297 <596f6354c96a891e58c04a09cbfb7b0d1ec00dab || >=61220ab349485d911083d0b7990ccd3db6c63297 <8b484efd5cb4eeef9021a661e198edc5349dacf6 | 94ff740a7f9ef5c010784a325dca00cbf228f941, df42ac708acc3399bbb6dc5ca16e0540adda7bbf, 44d2ff7d2178503b93151140a45dfa2ad49c9906, 1acfb7d9c6fc7e209ed7789392697e97e03edd33, d2236348414bdd6558385f35aa7fdc9bf5634011, 853f6ea482dfcd3404bbef458ab4d68364eed838, 596f6354c96a891e58c04a09cbfb7b0d1ec00dab, 8b484efd5cb4eeef9021a661e198edc5349dacf6 |
| Linux/Linuxgeneric | 3.15 | Not reported |
Published upstream
Jul 19, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 5, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 5, 2026
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 lookup returns NULL, t becomes self, and vti6_update() inserts the device into the creation netns hash. The new check requires CAP_NET_ADMIN in the creation netns user_ns too. SIOCADDTUNNEL and SIOCCHGTUNNEL on the fallback device keep dev_net(dev), which equals init_net there.
Quoted source text, attributed separately from HOL analysis.