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Review reviewHigh

CVE-2026-63921

Linux

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...

CVSS
8.8
EPSS
-
- percentile
CISA KEV
Not listed
Published
2026.07.20
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability-
Technical severityCVSS 8.8

Vulnerability overview

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...

Affected product and versions

Product
Linux
Affected versions
>= 61220ab349485d911083d0b7990ccd3db6c63297 < 94ff740a7f9ef5c010784a325dca00cbf228f941, >= 61220ab349485d911083d0b7990ccd3db6c63297 < df42ac708acc3399bbb6dc5ca16e0540adda7bbf, >= 61220ab349485d911083d0b7990ccd3db6c63297 < 44d2ff7d2178503b93151140a45dfa2ad49c9906, >= 61220ab349485d911083d0b7990ccd3db6c63297 < 1acfb7d9c6fc7e209ed7789392697e97e03edd33, >= 61220ab349485d911083d0b7990ccd3db6c63297 < d2236348414bdd6558385f35aa7fdc9bf5634011, >= 61220ab349485d911083d0b7990ccd3db6c63297 < 853f6ea482dfcd3404bbef458ab4d68364eed838, >= 61220ab349485d911083d0b7990ccd3db6c63297 < 596f6354c96a891e58c04a09cbfb7b0d1ec00dab, >= 61220ab349485d911083d0b7990ccd3db6c63297 < 8b484efd5cb4eeef9021a661e198edc5349dacf6, >= 3.15
Fixed versions
No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that Linux and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
CWE
Not available