CVE-2026-63921

HIGHPre-NVD 8.88.8—
EchelonGraph scoreMEDIUM confidence

Score 8.8 from GitHub Security Advisory (severity: HIGH) published 2026-07-19. the CNA's CVSS baseline 8.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cna:linux, epss, ghsa
Trending — 4 sources updated this week
8.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.8Exploit: None knownExposed: 0

A fix is available — apply it.

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.

CVSS v3
8.8
EG Score
8.8(medium)
EG Risk
44(Track)
EG Risk 44/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity88% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
7%
KEV
Not listed

Published

July 19, 2026

Last Modified

August 5, 2026

Advisory Details (8)

Auto-updated Jul 20, 2026
No patch confirmed yet.
generic

ip6: vti: Use ip6_tnl.net in vti6_siocdevprivate(). - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/8b484efd5cb4eeef9021a661e198edc5349dacf6
generic

ip6: vti: Use ip6_tnl.net in vti6_siocdevprivate(). - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/596f6354c96a891e58c04a09cbfb7b0d1ec00dab
generic

ip6: vti: Use ip6_tnl.net in vti6_siocdevprivate(). - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/853f6ea482dfcd3404bbef458ab4d68364eed838
generic

ip6: vti: Use ip6_tnl.net in vti6_siocdevprivate(). - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/d2236348414bdd6558385f35aa7fdc9bf5634011
generic

ip6: vti: Use ip6_tnl.net in vti6_siocdevprivate(). - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/1acfb7d9c6fc7e209ed7789392697e97e03edd33
generic

ip6: vti: Use ip6_tnl.net in vti6_siocdevprivate(). - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/44d2ff7d2178503b93151140a45dfa2ad49c9906
generic

ip6: vti: Use ip6_tnl.net in vti6_siocdevprivate(). - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/df42ac708acc3399bbb6dc5ca16e0540adda7bbf
generic

ip6: vti: Use ip6_tnl.net in vti6_siocdevprivate(). - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/94ff740a7f9ef5c010784a325dca00cbf228f941

Vendor Advisories for CVE-2026-63921(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(5)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulinux-tools-azure-fde-7.0 (7.0.0-1009.9) @ resolute2026-08-30ubuntu
ubuntulinux-tools-raspi-realtime-7.0 (7.0.0-1015.15) @ resolute2026-08-30ubuntu
ubuntulinux-tools-nvidia-hwe-24.04-edge (7.0.0-1016.16) @ resolute2026-08-30ubuntu
ubuntulinux-tools-nvidia-hwe-26.04 (7.0.0-2016.16) @ resolute2026-08-30ubuntu
ubuntulinux-tools-oracle-7.0 (7.0.0-1008.8) @ resolute2026-08-30ubuntu

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
linux5.10.103-1 ... 5.10.92-2 (54 versions)5.10.259-1—
Debian:12(1)
PackageVulnerable rangeFixed inDependents
linux6.1.106-1 ... 6.1.99-1 (53 versions)6.1.176-1—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
linux6.12.38-1 ... 6.12.94-1~bpo12+1 (27 versions)6.12.94-1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
linux6.12.100-1 ... 7.0.9-1~bpo13+1 (138 versions)7.0.12-1—

All Vendor Advisories

(5)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 32× in last 7d / 167× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 217 total refreshes for this CVE.

  1. 2026-08-30 02:57 UTCEG score recompute
  2. 2026-08-30 02:57 UTCVendor advisory
  3. 2026-08-30 02:57 UTCGHSA enrichment
  4. 2026-08-30 01:22 UTCEPSS rescore
  5. 2026-08-28 21:42 UTCEPSS rescore
  6. 2026-08-27 23:49 UTCEG score recompute
  7. 2026-08-27 23:49 UTCVendor advisory
  8. 2026-08-27 23:49 UTCGHSA enrichment
  9. 2026-08-27 14:25 UTCEPSS rescore
  10. 2026-08-27 12:12 UTCVendor advisory
  11. 2026-08-27 12:12 UTCGHSA enrichment
  12. 2026-08-27 00:57 UTCEG score recompute
  13. 2026-08-27 00:57 UTCVendor advisory
  14. 2026-08-27 00:57 UTCGHSA enrichment
  15. 2026-08-26 14:46 UTCEPSS rescore
  16. 2026-08-26 13:42 UTCVendor advisory
  17. 2026-08-26 13:42 UTCGHSA enrichment
  18. 2026-08-26 01:47 UTCVendor advisory
  19. 2026-08-26 01:47 UTCGHSA enrichment
  20. 2026-08-25 14:32 UTCEG score recompute
  21. 2026-08-25 14:32 UTCVendor advisory
  22. 2026-08-25 14:32 UTCGHSA enrichment
  23. 2026-08-25 13:49 UTCEPSS rescore
  24. 2026-08-25 03:08 UTCVendor advisory
  25. 2026-08-25 03:08 UTCGHSA enrichment
Show 75 more
  1. 2026-08-24 15:53 UTCEG score recompute
  2. 2026-08-24 15:53 UTCVendor advisory
  3. 2026-08-24 15:53 UTCGHSA enrichment
  4. 2026-08-24 04:27 UTCVendor advisory
  5. 2026-08-24 04:26 UTCGHSA enrichment
  6. 2026-08-23 17:12 UTCVendor advisory
  7. 2026-08-23 17:12 UTCGHSA enrichment
  8. 2026-08-23 05:58 UTCEG score recompute
  9. 2026-08-23 05:58 UTCVendor advisory
  10. 2026-08-23 05:58 UTCGHSA enrichment
  11. 2026-08-23 00:19 UTCEPSS rescore
  12. 2026-08-22 18:43 UTCVendor advisory
  13. 2026-08-22 18:43 UTCGHSA enrichment
  14. 2026-08-22 07:28 UTCEG score recompute
  15. 2026-08-22 07:28 UTCVendor advisory
  16. 2026-08-22 07:28 UTCGHSA enrichment
  17. 2026-08-21 23:49 UTCEPSS rescore
  18. 2026-08-21 20:13 UTCVendor advisory
  19. 2026-08-21 20:13 UTCGHSA enrichment
  20. 2026-08-21 08:59 UTCEG score recompute
  21. 2026-08-21 08:59 UTCVendor advisory
  22. 2026-08-21 08:59 UTCGHSA enrichment
  23. 2026-08-20 22:55 UTCEPSS rescore
  24. 2026-08-20 21:39 UTCVendor advisory
  25. 2026-08-20 21:39 UTCGHSA enrichment
  26. 2026-08-20 10:24 UTCVendor advisory
  27. 2026-08-20 10:24 UTCGHSA enrichment
  28. 2026-08-19 23:10 UTCEG score recompute
  29. 2026-08-19 23:10 UTCVendor advisory
  30. 2026-08-19 23:10 UTCGHSA enrichment
  31. 2026-08-19 17:04 UTCEPSS rescore
  32. 2026-08-19 07:55 UTCVendor advisory
  33. 2026-08-19 07:55 UTCGHSA enrichment
  34. 2026-08-18 20:40 UTCEG score recompute
  35. 2026-08-18 20:40 UTCVendor advisory
  36. 2026-08-18 20:40 UTCGHSA enrichment
  37. 2026-08-18 13:48 UTCEPSS rescore
  38. 2026-08-18 09:24 UTCVendor advisory
  39. 2026-08-18 09:24 UTCGHSA enrichment
  40. 2026-08-17 21:10 UTCEG score recompute
  41. 2026-08-17 21:10 UTCVendor advisory
  42. 2026-08-17 21:10 UTCGHSA enrichment
  43. 2026-08-17 13:47 UTCEPSS rescore
  44. 2026-08-17 06:35 UTCVendor advisory
  45. 2026-08-17 06:35 UTCGHSA enrichment
  46. 2026-08-16 19:17 UTCEG score recompute
  47. 2026-08-16 19:17 UTCVendor advisory
  48. 2026-08-16 19:17 UTCGHSA enrichment
  49. 2026-08-16 14:56 UTCEPSS rescore
  50. 2026-08-16 08:02 UTCEG score recompute
  51. 2026-08-16 08:02 UTCVendor advisory
  52. 2026-08-16 08:02 UTCGHSA enrichment
  53. 2026-08-15 20:48 UTCVendor advisory
  54. 2026-08-15 20:48 UTCGHSA enrichment
  55. 2026-08-15 09:33 UTCEG score recompute
  56. 2026-08-15 09:33 UTCVendor advisory
  57. 2026-08-15 09:33 UTCGHSA enrichment
  58. 2026-08-15 01:30 UTCEPSS rescore
  59. 2026-08-14 22:18 UTCVendor advisory
  60. 2026-08-14 22:18 UTCGHSA enrichment
  61. 2026-08-14 11:03 UTCVendor advisory
  62. 2026-08-14 11:03 UTCGHSA enrichment
  63. 2026-08-13 23:49 UTCEG score recompute
  64. 2026-08-13 23:49 UTCVendor advisory
  65. 2026-08-13 23:49 UTCGHSA enrichment
  66. 2026-08-13 22:00 UTCEPSS rescore
  67. 2026-08-13 12:34 UTCVendor advisory
  68. 2026-08-13 12:34 UTCGHSA enrichment
  69. 2026-08-13 01:18 UTCVendor advisory
  70. 2026-08-13 01:18 UTCGHSA enrichment
  71. 2026-08-12 14:04 UTCEG score recompute
  72. 2026-08-12 14:04 UTCVendor advisory
  73. 2026-08-12 14:04 UTCGHSA enrichment
  74. 2026-08-12 13:51 UTCEPSS rescore
  75. 2026-08-12 02:48 UTCVendor advisory

Related CVEs(same vendor)

Frequently asked(5)

What is CVE-2026-63921?
CVE-2026-63921 is a high vulnerability published on July 19, 2026. In the Linux kernel, the following vulnerability has been resolved: ip6: vti: Use ip6tnl.net in vti6siocdevprivate(). 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…
When was CVE-2026-63921 disclosed?
CVE-2026-63921 was first published in the National Vulnerability Database on July 19, 2026, with the most recent update on August 5, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-63921 actively exploited?
CVE-2026-63921 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 92.8% of all scored CVEs.
What is the CVSS score of CVE-2026-63921?
CVE-2026-63921 has a CVSS v4.0 base score of 8.8 (CNA self-assessment; NVD's own analysis pending).
How do I remediate CVE-2026-63921?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-63921, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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