IM
IronMonkey Threat Research

CVE-2026-43038 CRITICAL

Published: 2026-05-01 | Last Modified: 2026-07-15 | Status: Modified

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.

CVSS Metrics

Base Score: 9.8 (CRITICAL)

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack VectorNETWORK
Attack ComplexityLOW
Privileges RequiredNONE
User InteractionNONE
ScopeUNCHANGED
Confidentiality ImpactHIGH
Integrity ImpactHIGH
Availability ImpactHIGH

Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

Type: Secondary

Exploitability Score: 3.9

Impact Score: 5.9

Weaknesses

Source Type Description
[email protected] Primary
en NVD-CWE-noinfo
0b0ca135-0b70-47e7-9f44-1890c2a1c46c Secondary
en CWE-843

Affected Products

Vendor Product Version Update Type
linux linux_kernel * <built-in method update of dict object at 0x702bde534180> Operating System
linux linux_kernel * <built-in method update of dict object at 0x702bde536440> Operating System
linux linux_kernel * <built-in method update of dict object at 0x702bde534280> Operating System
linux linux_kernel * <built-in method update of dict object at 0x702bde534600> Operating System
linux linux_kernel * <built-in method update of dict object at 0x702bde537b40> Operating System
linux linux_kernel * <built-in method update of dict object at 0x702bde536cc0> Operating System
linux linux_kernel * <built-in method update of dict object at 0x702bde534840> Operating System
linux linux_kernel 3.13 <built-in method update of dict object at 0x702bde5362c0> Operating System
linux linux_kernel 3.13 <built-in method update of dict object at 0x702bdc9f6480> Operating System
linux linux_kernel 3.13 <built-in method update of dict object at 0x702bde535a80> Operating System
linux linux_kernel 3.13 <built-in method update of dict object at 0x702bde5358c0> Operating System
linux linux_kernel 3.13 <built-in method update of dict object at 0x702bdc9f4600> Operating System
linux linux_kernel 3.13 <built-in method update of dict object at 0x702bdd1294c0> Operating System
linux linux_kernel 3.13 <built-in method update of dict object at 0x702b83f2e980> Operating System
linux linux_kernel 7.0 <built-in method update of dict object at 0x702bdc4fec00> Operating System
linux linux_kernel 7.0 <built-in method update of dict object at 0x702bde537340> Operating System
linux linux_kernel 7.0 <built-in method update of dict object at 0x702bde537c80> Operating System
linux linux_kernel 7.0 <built-in method update of dict object at 0x702b83f2d300> Operating System
linux linux_kernel 7.0 <built-in method update of dict object at 0x702bde534d00> Operating System
linux linux_kernel 7.0 <built-in method update of dict object at 0x702bdd129240> Operating System

Affected Configurations

Operator: OR

Vulnerable CPE
Yes cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Yes cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Yes cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Yes cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Yes cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Yes cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Yes cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Yes cpe:2.3:o:linux:linux_kernel:3.13:-:*:*:*:*:*:*
Yes cpe:2.3:o:linux:linux_kernel:3.13:rc3:*:*:*:*:*:*
Yes cpe:2.3:o:linux:linux_kernel:3.13:rc4:*:*:*:*:*:*
Yes cpe:2.3:o:linux:linux_kernel:3.13:rc5:*:*:*:*:*:*
Yes cpe:2.3:o:linux:linux_kernel:3.13:rc6:*:*:*:*:*:*
Yes cpe:2.3:o:linux:linux_kernel:3.13:rc7:*:*:*:*:*:*
Yes cpe:2.3:o:linux:linux_kernel:3.13:rc8:*:*:*:*:*:*
Yes cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*
Yes cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*
Yes cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*
Yes cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*
Yes cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:*
Yes cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:*

References

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