Skip to main content
VulnerabilityPublished Updated

CVE-2026-53228: Linux kernel · ipv6: sit: reload inner IPv6 header after GSO offloads

Affects Linux kernelSource GCVE Database

0
Authoritative record:CVE-2026-53228· Critical 9.8

Not known to be exploited · CVSS 9.8 Critical · patch available : patch Linux kernel as a priority.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.5% chance of exploitation in 30 days – higher than 47% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 25 Jun 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
Ubuntu 26.04 LTSlinuxpkg:deb/ubuntu/linux@7.0.0-28.28?arch=source&distro=resoluteOther threatsAffected
  • 6.17.0-5.5 – 7.0.0-28.28
18 affected builds
Fixed in–
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws@7.0.0-1008.8?arch=source&distro=resoluteOther threatsAffected
  • 6.17.0-1002.2 – 7.0.0-1008.8
9 affected builds
Fixed in–
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure@7.0.0-1009.9?arch=source&distro=resoluteOther threatsAffected
  • 6.17.0-1003.3 – 7.0.0-1009.9
10 affected builds
Fixed in–
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde@7.0.0-1008.8?arch=source&distro=resoluteOther threatsAffected
  • 7.0.0-1003.3 – 7.0.0-1008.8
4 affected builds
Fixed in–
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp@7.0.0-1008.8?arch=source&distro=resoluteOther threatsAffected
  • 6.17.0-1002.2 – 7.0.0-1008.8
9 affected builds
Fixed in–
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke@7.0.0-1003.4?arch=source&distro=resoluteOther threatsAffected
  • =7.0.0-1002.3
  • =7.0.0-1003.4
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

In the Linux kernel, the following vulnerability has been resolved: ipv6: sit: reload inner IPv6 header after GSO offloads ipip6_tunnel_xmit() caches the inner IPv6 header pointer at function entry and continues using it after iptunnel_handle_offloads(). For GSO skbs, iptunnel_handle_offloads() calls skb_header_unclone(). When the skb header is cloned, skb_header_unclone() can call pskb_expand_head(), which may move the skb head. The pskb_expand_head() contract requires pointers into the skb header to be reloaded after the call. If the later skb_realloc_headroom() branch is not taken, SIT uses the stale iph6 pointer to read the inner hop limit and DS field. That can read from a freed skb head after the old head's remaining clone is released. Reload iph6 after the offload helper succeeds and before subsequent reads from the inner IPv6 header. Keep the existing reload after skb_realloc_headroom(), since that branch can also replace the skb.

References

Community reviews

Loading reviews…