Live › vulnerability › CVE-2026-98532
Go to dashboardThe IPv6 extension header walker in the Linux kernel could return an offset past the end of a packet when a header declared a length larger than the packet. Open vSwitch then used that offset to read and write the transport checksum out of bounds, which can corrupt kernel memory.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-10-23 21:57 UTC. All times on this page are UTC.
Systems running a Linux kernel with IPv6 extension header handling and Open vSwitch in the datapath, where IPv6 traffic with crafted extension headers reaches OVS actions that rewrite IPv6 addresses. Hosts that do not load openvswitch and do not use IPv6 extension header paths in the affected code are less exposed. The sources do not state which kernel versions are affected.
No product ranges from the sources yet.
uname -r and compare against the fixed kernel builds listed by your distribution's security tracker for CVE-2026-98532lsmod | grep openvswitchEach row is the first time that source carried this signal. The analyst’s rows are its own findings.
In the Linux kernel, the following vulnerability has been resolved:
ipv6: do not let ipv6_find_hdr() return an offset past the packet end
ipv6_find_hdr() walks the extension header chain, skipping each header by the length that header itself declares. ipv6_optlen() returns up to 2048, and the skip is never checked against skb->len, so the offset stored in *offset can point past the end of the packet.
openvswitch installs that offset as the transport header, and update_ipv6_checksum() then reads and writes the transport checksum field out of bounds:
BUG: KASAN: slab-use-after-free in inet_proto_csum_replace16+0x445/0x470 Read of size 2 at addr ffff88810b754b06 by task ovs_ipv6_oob/629 CPU: 4 UID: 1000 PID: 629 Comm: ovs_ipv6_oob Tainted: G N 7.3.0-rc3+ #348 Call Trace: inet_proto_csum_replace16+0x445/0x470 set_ipv6_addr+0x3dd/0x460 do_execute_actions+0x6a3d/0x7c40 ovs_execute_actions+0xfd/0x480 ovs_packet_cmd_execute+0xc38/0xf20 genl_rcv_msg+0x59e/0x870 netlink_rcv_skb+0x18b/0x450 genl_rcv+0x2d/0x40 netlink_unicast+0x6bc/0xa20
The buggy address belongs to the object at ffff88810b754980 which belongs to the cache skbuff_small_head of size 704 The buggy address is located 390 bytes inside of freed 704-byte region [ffff88810b754980, ffff88810b754c40)
Other callers use that offset too, so bound it here rather than in one caller.
Reject a header whose declared length does not fit in the packet. ipv6_find_hdr() already fails with -EBADMSG on a malformed chain, so this adds no new failure mode.
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