In the Linux kernel, the following vulnerability has been resolved: ipv6: icmp: clear skb2->cb[] in ip6_err_gen_icmpv6_unreach() Sashiko AI-review observed: In ip6_err_gen_icmpv6_unreach(), the skb is an outer IPv4 ICMP error packet where its cb contains an IPv4 inet_skb_parm. When skb is cloned into skb2 and passed to icmp6_send(), it uses IP6CB(skb2). IP6CB interprets the IPv4 inet_skb_parm as an inet6_skb_parm. The cipso offset in inet_skb_parm.opt directly overlaps with dsthao in inet6_skb_parm at offset 18. If an attacker sends a forged ICMPv4 error with a CIPSO IP option, dsthao would be a non-zero offset. Inside icmp6_send(), mip6_addr_swap() is called and uses ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO). This would scan the inner, attacker-controlled IPv6 packet starting at that offset, potentially returning a fake TLV without checking if the remaining packet length can hold the full 18-byte struct ipv6_destopt_hao. Could mip6_addr_swap() then perform a 16-byte swap that extends past the end of the packet data into skb_shared_info? Should the cb array also be cleared in ip6_err_gen_icmpv6_unreach() and ip6ip6_err() to prevent this? This patch implements the first suggestion. I am not sure if ip6ip6_err() needs to be changed. A separate patch would be better anyway.
Upstream advisory: https://lore.kernel.org/linux-cve-announce/2026050103-CVE-2026-43038-b591@gregkh/T
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions Via RHSA-2026:22900 https://access.redhat.com/errata/RHSA-2026:22900
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions Via RHSA-2026:22940 https://access.redhat.com/errata/RHSA-2026:22940
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions Via RHSA-2026:23237 https://access.redhat.com/errata/RHSA-2026:23237
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.6 Extended Update Support Via RHSA-2026:23224 https://access.redhat.com/errata/RHSA-2026:23224
This issue has been addressed in the following products: Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions Red Hat Enterprise Linux 8.8 Telecommunications Update Service Via RHSA-2026:22964 https://access.redhat.com/errata/RHSA-2026:22964
This issue has been addressed in the following products: Red Hat Enterprise Linux 10.0 Extended Update Support Via RHSA-2026:24343 https://access.redhat.com/errata/RHSA-2026:24343
This issue has been addressed in the following products: Red Hat Enterprise Linux 8 Via RHSA-2026:25120 https://access.redhat.com/errata/RHSA-2026:25120
This issue has been addressed in the following products: Red Hat Enterprise Linux 8 Via RHSA-2026:25121 https://access.redhat.com/errata/RHSA-2026:25121
This issue has been addressed in the following products: Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support Via RHSA-2026:25533 https://access.redhat.com/errata/RHSA-2026:25533
This issue has been addressed in the following products: Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On Via RHSA-2026:26535 https://access.redhat.com/errata/RHSA-2026:26535