Vulnerability Database

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Total vulnerabilities in the database

CVE-2026-43038 — linux / linux_kernel

Access of Resource Using Incompatible Type ('Type Confusion')

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.

  • Published: May 1, 2026
  • Updated: May 3, 2026
  • CVE: CVE-2026-43038
  • Severity: Critical
  • Exploit:
  • CISA KEV:

CVSS v3:

  • Severity: Critical
  • Score: 9.8
  • AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CWEs:

Software From Fixed in
linux / linux_kernel 3.13.x 5.10.253
linux / linux_kernel 5.11 5.15.203
linux / linux_kernel 5.16 6.1.168
linux / linux_kernel 6.2 6.6.134
linux / linux_kernel 6.7 6.12.81
linux / linux_kernel 6.13 6.18.22
linux / linux_kernel 6.19 6.19.12
linux / linux_kernel 3.13 3.13.x
linux / linux_kernel 3.13-rc3 3.13-rc3.x
linux / linux_kernel 3.13-rc4 3.13-rc4.x
linux / linux_kernel 3.13-rc5 3.13-rc5.x
linux / linux_kernel 3.13-rc6 3.13-rc6.x
linux / linux_kernel 3.13-rc7 3.13-rc7.x
linux / linux_kernel 3.13-rc8 3.13-rc8.x
linux / linux_kernel 7.0-rc1 7.0-rc1.x
linux / linux_kernel 7.0-rc2 7.0-rc2.x
linux / linux_kernel 7.0-rc3 7.0-rc3.x
linux / linux_kernel 7.0-rc4 7.0-rc4.x
linux / linux_kernel 7.0-rc5 7.0-rc5.x
linux / linux_kernel 7.0-rc6 7.0-rc6.x

Frequently Asked Questions

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