Description
In the Linux kernel, the following vulnerability has been resolved:

net: openvswitch: validate transport header presence in set_ipv6_addr

When executing IPv6 address rewrite actions on IPv6 fragments,
set_ipv6_addr() calls update_ipv6_checksum(). If parse_ipv6hdr()
processes a non-first IPv6 fragment, it sets key->ip.proto to
NEXTHDR_FRAGMENT and returns early without calling
skb_set_transport_header().

update_ipv6_checksum() unconditionally evaluates skb_transport_offset()
on entry before checking l4_proto. Because skb->transport_header is
uninitialized, this triggers a warning under CONFIG_DEBUG_NET=y although
it is completely harmless.

Fix this by returning early in update_ipv6_checksum() if l4_proto is
NEXTHDR_FRAGMENT. This avoids reading the uninitialized transport offset
for fragments while preserving the debug warning for any other protocol
where the transport header is unexpectedly missing.

See the syzbot trace:

!skb_transport_header_was_set(skb)
WARNING: ./include/linux/skbuff.h:3075 at skb_transport_header include/linux/skbuff.h:3075 [inline], CPU#1: syz-executor463/5635
WARNING: ./include/linux/skbuff.h:3075 at skb_transport_offset include/linux/skbuff.h:3250 [inline], CPU#1: syz-executor463/5635
WARNING: ./include/linux/skbuff.h:3075 at update_ipv6_checksum net/openvswitch/actions.c:361 [inline], CPU#1: syz-executor463/5635
WARNING: ./include/linux/skbuff.h:3075 at set_ipv6_addr+0x462/0x660 net/openvswitch/actions.c:399, CPU#1: syz-executor463/5635
[...]
RIP: 0010:skb_transport_header include/linux/skbuff.h:3075 [inline]
RIP: 0010:skb_transport_offset include/linux/skbuff.h:3250 [inline]
RIP: 0010:update_ipv6_checksum net/openvswitch/actions.c:361 [inline]
RIP: 0010:set_ipv6_addr+0x462/0x660 net/openvswitch/actions.c:399
[...]
Call Trace:
<TASK>
set_ipv6 net/openvswitch/actions.c:531 [inline]
do_execute_actions+0x557e/0x8600 net/openvswitch/actions.c:1366
ovs_execute_actions+0xde/0x520 net/openvswitch/actions.c:1592
ovs_packet_cmd_execute+0xb4f/0xf10 net/openvswitch/datapath.c:705
genl_family_rcv_msg_doit+0x233/0x340 net/netlink/genetlink.c:1114
genl_rcv_msg+0x614/0x7a0 net/netlink/genetlink.c:1209
netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2572
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218
netlink_unicast+0x7bd/0x940 net/netlink/af_netlink.c:1361
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1916
sock_sendmsg_nosec+0x14e/0x190 net/socket.c:800
Published: 2026-10-26
Score: n/a
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Analysis and contextual insights are available on OpenCVE Cloud.

Remediation

No vendor fix or workaround currently provided.

Additional remediation guidance may be available on OpenCVE Cloud.

Tracking

Sign in to view the affected projects.

Advisories

No advisories yet.

History

Mon, 26 Oct 2026 17:00:00 +0000

Type Values Removed Values Added
Weaknesses CWE-457

Mon, 26 Oct 2026 15:00:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: net: openvswitch: validate transport header presence in set_ipv6_addr When executing IPv6 address rewrite actions on IPv6 fragments, set_ipv6_addr() calls update_ipv6_checksum(). If parse_ipv6hdr() processes a non-first IPv6 fragment, it sets key->ip.proto to NEXTHDR_FRAGMENT and returns early without calling skb_set_transport_header(). update_ipv6_checksum() unconditionally evaluates skb_transport_offset() on entry before checking l4_proto. Because skb->transport_header is uninitialized, this triggers a warning under CONFIG_DEBUG_NET=y although it is completely harmless. Fix this by returning early in update_ipv6_checksum() if l4_proto is NEXTHDR_FRAGMENT. This avoids reading the uninitialized transport offset for fragments while preserving the debug warning for any other protocol where the transport header is unexpectedly missing. See the syzbot trace: !skb_transport_header_was_set(skb) WARNING: ./include/linux/skbuff.h:3075 at skb_transport_header include/linux/skbuff.h:3075 [inline], CPU#1: syz-executor463/5635 WARNING: ./include/linux/skbuff.h:3075 at skb_transport_offset include/linux/skbuff.h:3250 [inline], CPU#1: syz-executor463/5635 WARNING: ./include/linux/skbuff.h:3075 at update_ipv6_checksum net/openvswitch/actions.c:361 [inline], CPU#1: syz-executor463/5635 WARNING: ./include/linux/skbuff.h:3075 at set_ipv6_addr+0x462/0x660 net/openvswitch/actions.c:399, CPU#1: syz-executor463/5635 [...] RIP: 0010:skb_transport_header include/linux/skbuff.h:3075 [inline] RIP: 0010:skb_transport_offset include/linux/skbuff.h:3250 [inline] RIP: 0010:update_ipv6_checksum net/openvswitch/actions.c:361 [inline] RIP: 0010:set_ipv6_addr+0x462/0x660 net/openvswitch/actions.c:399 [...] Call Trace: <TASK> set_ipv6 net/openvswitch/actions.c:531 [inline] do_execute_actions+0x557e/0x8600 net/openvswitch/actions.c:1366 ovs_execute_actions+0xde/0x520 net/openvswitch/actions.c:1592 ovs_packet_cmd_execute+0xb4f/0xf10 net/openvswitch/datapath.c:705 genl_family_rcv_msg_doit+0x233/0x340 net/netlink/genetlink.c:1114 genl_rcv_msg+0x614/0x7a0 net/netlink/genetlink.c:1209 netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2572 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218 netlink_unicast+0x7bd/0x940 net/netlink/af_netlink.c:1361 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1916 sock_sendmsg_nosec+0x14e/0x190 net/socket.c:800
Title net: openvswitch: validate transport header presence in set_ipv6_addr
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-10-26T14:51:58.460Z

Reserved: 2026-09-25T10:25:14.390Z

Link: CVE-2026-99088

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-10-26T15:16:47.517

Modified: 2026-10-26T15:16:47.517

Link: CVE-2026-99088

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-26T16:45:14Z

Weaknesses