Bug 2502444 (CVE-2026-63994) - CVE-2026-63994 kernel: tunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]()
Summary: CVE-2026-63994 kernel: tunnels: load network headers after skb_cow() in iptun...
Keywords:
Status: NEW
Alias: CVE-2026-63994
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
high
high
Target Milestone: ---
Assignee: Product Security
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-07-19 16:08 UTC by OSIDB Bzimport
Modified: 2026-11-11 04:13 UTC (History)
2 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2026:75746 0 None None None 2026-10-05 10:48:46 UTC
Red Hat Product Errata RHSA-2026:75747 0 None None None 2026-10-05 11:23:53 UTC
Red Hat Product Errata RHSA-2026:76738 0 None None None 2026-10-07 20:29:14 UTC
Red Hat Product Errata RHSA-2026:76739 0 None None None 2026-10-08 09:50:14 UTC
Red Hat Product Errata RHSA-2026:98047 0 None None None 2026-11-11 00:42:05 UTC
Red Hat Product Errata RHSA-2026:98239 0 None None None 2026-11-11 04:13:11 UTC

Description OSIDB Bzimport 2026-07-19 16:08:31 UTC 
In the Linux kernel, the following vulnerability has been resolved:

tunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]()

Sashiko found that iptunnel_pmtud_build_icmp() and
iptunnel_pmtud_build_icmpv6() were caching ip_hdr() and ipv6_hdr()
before an skb_cow() call which can reallocate skb->head.

Fix this possible UAF by initializing the local variables
after the skb_cow() call.

Remove skb_reset_network_header() calls which were not needed.
Comment 1 Mauro Matteo Cascella 2026-07-21 14:43:38 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026071905-CVE-2026-63994-97bf@gregkh/T
Comment 4 Jon Orris 2026-10-05 10:48:46 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:75746 https://access.redhat.com/errata/RHSA-2026:75746
Comment 5 Jon Orris 2026-10-05 11:23:51 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:75747 https://access.redhat.com/errata/RHSA-2026:75747
Comment 6 Jon Orris 2026-10-07 20:29:14 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:76738 https://access.redhat.com/errata/RHSA-2026:76738
Comment 7 Jon Orris 2026-10-08 09:50:13 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:76739 https://access.redhat.com/errata/RHSA-2026:76739
Comment 8 errata-xmlrpc 2026-11-11 00:42:04 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions

Via RHSA-2026:98047 https://access.redhat.com/errata/RHSA-2026:98047
Comment 9 errata-xmlrpc 2026-11-11 04:13:10 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.6 Extended Update Support

Via RHSA-2026:98239 https://access.redhat.com/errata/RHSA-2026:98239
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