Copyright © 2012 Red Hat, Inc. All rights reserved. Important 2026-10-18T00:00:00 kernel: ipv6: do not let ipv6_find_hdr() return an offset past the packet end 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CWE-787

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.

A flaw was found in the Linux kernel. A remote attacker could cause a Denial of Service (DoS) or memory corruption by sending specially crafted IPv6 network packets. The IPv6 extension header parsing mechanism fails to verify that the declared length of a header fits within the received packet data, resulting in an offset that points past the end of the buffer. Subsequent networking operations that process this invalid offset perform out-of-bounds memory reads and writes, triggering a kernel crash.

This vulnerability is rated as having an Important impact because an unauthenticated remote attacker can cause a denial of service by transmitting malformed IPv6 packets across the network without requiring privileges or user interaction. In standard Red Hat Enterprise Linux and OpenShift deployments, the IPv6 networking stack is enabled by default, leaving systems exposed if they receive untrusted external traffic or utilize packet inspection frameworks like Open vSwitch. Although out-of-bounds memory operations occur during header parsing, the primary risk in production environments is an immediate kernel panic resulting in system downtime. --- CME Mitigation Guidance (2026-10-20) --- Disclaimer: The following mitigation solutions are provided as a courtesy, pending the application of an official patch. This content was generated utilizing AI tools in conjunction with data from https://cmetaxonomy.org. Customers are advised to independently evaluate and test these temporary mitigations within their own infrastructure. The highest-value action is to enforce packet length bounds checks against skb->len within ipv6_find_hdr() extension header processing: upgrade to the fixed Kernel/Kernel Rt/Kernel Ivos Qualcomm/Openshift/Ose Rhel Coreos/Kpatch builds, which reject an extension header and return -EBADMSG if its declared length exceeds the remaining packet bytes (skb->len - start), closing all 2 injection vectors (crafted IPv6 network packet with oversized extension header length, Netlink packet command execution triggering Open vSwitch transport header parsing). Until patched, this is a concern on Linux systems running IPv6 networking stack, so restrict untrusted IPv6 traffic or disable unneeded IPv6 packet processing interfaces. As a compensating measure, enable kernel memory allocation error detection (KASAN/HWASan) to detect out-of-bounds slab memory accesses during IPv6 extension header parsing. These controls limit blast radius and contain exploitation, but they do not fix the underlying out-of-bounds memory read and write defect — apply the upstream patch to fully remediate. Highest-impact CME: CME-1005 Runtime Memory Error Detection (KASAN/HWASan) (medium) Red Hat Enterprise Linux 10 Affected kernel Red Hat Enterprise Linux 6 Under investigation kernel Red Hat Enterprise Linux 7 Affected kernel Red Hat Enterprise Linux 7 Affected kernel-rt Red Hat Enterprise Linux 8 Affected kernel Red Hat Enterprise Linux 8 Affected kernel-rt Red Hat Enterprise Linux 9 Affected kernel Red Hat Enterprise Linux 9 Affected kernel-rt Red Hat OpenShift Container Platform 4 Affected openshift/ose-rhel-coreos-8 Red Hat OpenShift Container Platform 4 Affected openshift/ose-rhel-coreos-9 Red Hat OpenShift Container Platform 5 Affected openshift/ose-rhel-coreos-9 https://www.cve.org/CVERecord?id=CVE-2026-98532 https://nvd.nist.gov/vuln/detail/CVE-2026-98532 https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98532.mbox