cbcvebase.
CVE-2026-43038
published 2026-05-01

CVE-2026-43038: 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…

PriorityP351critical9.8CVSS 3.1
AVNACLPRNUINSUCHIHAH
EPSS
0.26%
17.1th percentile
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.

Affected

78 ranges· showing 25
VendorProductVersion rangeFixed in
linuxlinux
linuxlinux>= ca15a078bd907df5fc1c009477869c5cbde3b753 < c438ba010171b70bad22fc18b1d5bdc3627476e8c438ba010171b70bad22fc18b1d5bdc3627476e8
linuxlinux>= ca15a078bd907df5fc1c009477869c5cbde3b753 < 0452b6526b2f54b2413b9cb4ff1ea2ac542c99c70452b6526b2f54b2413b9cb4ff1ea2ac542c99c7
linuxlinux>= ca15a078bd907df5fc1c009477869c5cbde3b753 < a4437faf135da293d16fcc4cc607316742bd0ebba4437faf135da293d16fcc4cc607316742bd0ebb
linuxlinux>= ca15a078bd907df5fc1c009477869c5cbde3b753 < 3d5127d998de617b130aae96b138dba22ac6a8a73d5127d998de617b130aae96b138dba22ac6a8a7
linuxlinux>= ca15a078bd907df5fc1c009477869c5cbde3b753 < e41953e7d118e2702bcb217879c173d9d1d3cd4ee41953e7d118e2702bcb217879c173d9d1d3cd4e
linuxlinux>= ca15a078bd907df5fc1c009477869c5cbde3b753 < a2edbb6393972a02114b6003953a5cef3104fadaa2edbb6393972a02114b6003953a5cef3104fada
linuxlinux>= ca15a078bd907df5fc1c009477869c5cbde3b753 < 1ceeebd5bd6d855b17a5df625109bfe29129d7cf1ceeebd5bd6d855b17a5df625109bfe29129d7cf
linuxlinux>= ca15a078bd907df5fc1c009477869c5cbde3b753 < 86ab3e55673a7a49a841838776f1ab18d23a67b586ab3e55673a7a49a841838776f1ab18d23a67b5
linuxlinux_kernel< 5.10.2535.10.253
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel>= 5.11 < 5.15.2035.15.203

CVSS provenance

nvdv3.19.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
vendor_ubuntu8.8HIGH
vendor_redhat7.0HIGH
Stop checking back — get the weekly exploitation signal.

Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.