CVE-2026-53228: Linux kernel · ipv6: sit: reload inner IPv6 header after GSO offloads
Affects Linux kernelSource GCVE Database
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
- 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:HExploitation evidence
Disclosed: evidence found.
CVE published 25 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSlinuxpkg:deb/ubuntu/linux@7.0.0-28.28?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws@7.0.0-1008.8?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure@7.0.0-1009.9?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde@7.0.0-1008.8?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp@7.0.0-1008.8?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke@7.0.0-1003.4?arch=source&distro=resoluteOther threats | Affected
| 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
- ubuntu.com/security/CVE-2026-53228 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-53228 (opens in a new tab)
- git.kernel.org/linus/f0e42f0c4337b1f220de1ddd63f47197c7dee4de (opens in a new tab)
- git.kernel.org/stable/c/0bfa7bba1f41aaf5f0604dc712bb4701493e3aa0 (opens in a new tab)
- git.kernel.org/stable/c/1132e5edc2866c3530be17622153a597095f0e43 (opens in a new tab)
- git.kernel.org/stable/c/2fa49b2715e1bad12ce3b0fa64e234d9582c8193 (opens in a new tab)
- git.kernel.org/stable/c/59f80c919713250fe5d25a4d9aea4e49580fa1d4 (opens in a new tab)
- git.kernel.org/stable/c/9c67b44edb3598d234efae6e44649eb993c03da5 (opens in a new tab)
- git.kernel.org/stable/c/cb658c2f5f7977c2a1c77c9f239f4bc8196edb5c (opens in a new tab)
- git.kernel.org/stable/c/f0e42f0c4337b1f220de1ddd63f47197c7dee4de (opens in a new tab)
- git.kernel.org/stable/c/fddd41445a0537b093e6b3f6232c9933cad1e48b (opens in a new tab)
- ubuntu.com/security/notices/USN-8629-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8630-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8631-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8633-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8635-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8636-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8630-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8631-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8637-1 (opens in a new tab)