CVE-2026-99088

net: openvswitch: validate transport header presence in set_ipv6_addr

State: Published
Severity: Not scored
Published: Oct 26, 2026
Updated: Oct 30, 2026
Reserved: Sep 25, 2026

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

Scores

The record has no CVSS score.

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	3fdbd1ce11e5c0d7cafbe44c942c5cad61113d7b to before 1efa6842e94aa70237446b31fbe2bc16586809c3Affected 3fdbd1ce11e5c0d7cafbe44c942c5cad61113d7b to before ad4258db21e801a7aae614afca89a2e39283080dAffected 3fdbd1ce11e5c0d7cafbe44c942c5cad61113d7b to before 54cb98ed23866205926298621e04169f50665b59Affected 3fdbd1ce11e5c0d7cafbe44c942c5cad61113d7b to before b7b80d204abdc258006f9e17c92b363ab13bb599Affected 3fdbd1ce11e5c0d7cafbe44c942c5cad61113d7b to before 6774af7cd17be8f0d0f70de3a749d381b4f2e9daAffected 3fdbd1ce11e5c0d7cafbe44c942c5cad61113d7b to before 2594795fd832f0253826d64ff8976b8ff5fbfe9fAffected 3fdbd1ce11e5c0d7cafbe44c942c5cad61113d7b to before 6b8897ba0733f88f0360ea48a970f373f9142de0Affected 3fdbd1ce11e5c0d7cafbe44c942c5cad61113d7b to before 3c6a4b11330fe424557538a98fca9f0a4c5bf313Affected
LinuxLinux	3.8Affected before 3.8Not affected 5.10.273 through 5.10.Not affected 5.15.224 through 5.15.Not affected 6.1.191 through 6.1.Not affected 6.6.160 through 6.6.Not affected 6.12.113 through 6.12.Not affected 6.18.57 through 6.18.Not affected 7.2.11 through 7.2.*Not affected 7.3 and laterNot affected

Product

Versions

LinuxLinux

3fdbd1ce11e5c0d7cafbe44c942c5cad61113d7b to before 1efa6842e94aa70237446b31fbe2bc16586809c3Affected
3fdbd1ce11e5c0d7cafbe44c942c5cad61113d7b to before ad4258db21e801a7aae614afca89a2e39283080dAffected
3fdbd1ce11e5c0d7cafbe44c942c5cad61113d7b to before 54cb98ed23866205926298621e04169f50665b59Affected
3fdbd1ce11e5c0d7cafbe44c942c5cad61113d7b to before b7b80d204abdc258006f9e17c92b363ab13bb599Affected
3fdbd1ce11e5c0d7cafbe44c942c5cad61113d7b to before 6774af7cd17be8f0d0f70de3a749d381b4f2e9daAffected
3fdbd1ce11e5c0d7cafbe44c942c5cad61113d7b to before 2594795fd832f0253826d64ff8976b8ff5fbfe9fAffected
3fdbd1ce11e5c0d7cafbe44c942c5cad61113d7b to before 6b8897ba0733f88f0360ea48a970f373f9142de0Affected
3fdbd1ce11e5c0d7cafbe44c942c5cad61113d7b to before 3c6a4b11330fe424557538a98fca9f0a4c5bf313Affected

LinuxLinux

3.8Affected
before 3.8Not affected
5.10.273 through 5.10.*Not affected
5.15.224 through 5.15.*Not affected
6.1.191 through 6.1.*Not affected
6.6.160 through 6.6.*Not affected
6.12.113 through 6.12.*Not affected
6.18.57 through 6.18.*Not affected
7.2.11 through 7.2.*Not affected
7.3 and laterNot affected

References

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