Skip to content
CVE PROGRAM SOURCE RECORD9.8 Critical

CVE-2026-43038

ipv6: icmp: clear skb2->cb[] in ip6_err_gen_icmpv6_unreach()

Read JSON ↗CVE.org ↗
Status
Published
Published
Updated
Assigning organization
Linux

Description

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 products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • ca15a078bd907df5fc1c009477869c5cbde3b753 to < c438ba010171b70bad22fc18b1d5bdc3627476e8affected
  • ca15a078bd907df5fc1c009477869c5cbde3b753 to < 0452b6526b2f54b2413b9cb4ff1ea2ac542c99c7affected
  • ca15a078bd907df5fc1c009477869c5cbde3b753 to < a4437faf135da293d16fcc4cc607316742bd0ebbaffected
  • ca15a078bd907df5fc1c009477869c5cbde3b753 to < 3d5127d998de617b130aae96b138dba22ac6a8a7affected
  • ca15a078bd907df5fc1c009477869c5cbde3b753 to < e41953e7d118e2702bcb217879c173d9d1d3cd4eaffected
  • ca15a078bd907df5fc1c009477869c5cbde3b753 to < a2edbb6393972a02114b6003953a5cef3104fadaaffected
  • ca15a078bd907df5fc1c009477869c5cbde3b753 to < 1ceeebd5bd6d855b17a5df625109bfe29129d7cfaffected
  • ca15a078bd907df5fc1c009477869c5cbde3b753 to < 86ab3e55673a7a49a841838776f1ab18d23a67b5affected

Linux Linux

Default version status: affected

  • 3.13affected
  • 0 to < 3.13unaffected
  • 5.10.253 to ≤ 5.10.*unaffected
  • 5.15.203 to ≤ 5.15.*unaffected
  • 6.1.168 to ≤ 6.1.*unaffected
  • 6.6.134 to ≤ 6.6.*unaffected
  • 6.12.81 to ≤ 6.12.*unaffected
  • 6.18.22 to ≤ 6.18.*unaffected
  • 6.19.12 to ≤ 6.19.*unaffected
  • 7.0 to ≤ *unaffected

References