CVE-2026-43038ipv6: icmp: clear skb2->cb[] in ip6_err_gen_icmpv6_unreach()
Updated under an hour ago ()
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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
- 9.8 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Weakness (CWE)
- CWE-843
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Modified
- Record last updated
- Oct 16, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | from ca15a078bd907df5fc1c009477869c5cbde3b753 before c438ba010171b70bad22fc18b1d5bdc3627476e8; from ca15a078bd907df5fc1c009477869c5cbde3b753 before 0452b6526b2f54b2413b9cb4ff1ea2ac542c99c7; from ca15a078bd907df5fc1c009477869c5cbde3b753 before a4437faf135da293d16fcc4cc607316742bd0ebb; from ca15a078bd907df5fc1c009477869c5cbde3b753 before 3d5127d998de617b130aae96b138dba22ac6a8a7; from ca15a078bd907df5fc1c009477869c5cbde3b753 before e41953e7d118e2702bcb217879c173d9d1d3cd4e; from ca15a078bd907df5fc1c009477869c5cbde3b753 before a2edbb6393972a02114b6003953a5cef3104fada; from ca15a078bd907df5fc1c009477869c5cbde3b753 before 1ceeebd5bd6d855b17a5df625109bfe29129d7cf; from ca15a078bd907df5fc1c009477869c5cbde3b753 before 86ab3e55673a7a49a841838776f1ab18d23a67b5 | CNA record |
Red Hat Red Hat Enterprise Linux 10 redhat:enterprise_linux | from 0:6.12.0-211.28.1.el10_2 not affected | CISA ADP |
Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support redhat:enterprise_linux_eus | from 0:6.12.0-55.77.1.el10_0 not affected | CISA ADP |
from 0:4.18.0-305.194.1.el8_4 not affected | CISA ADP | |
Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On redhat:rhel_eus_long_life | from 0:4.18.0-305.194.1.el8_4 not affected | CISA ADP |
from 0:4.18.0-477.145.1.el8_8 not affected | CISA ADP | |
from 0:4.18.0-477.145.1.el8_8 not affected | CISA ADP | |
Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support redhat:rhel_eus | from 0:5.14.0-570.119.1.el9_6 not affected | CISA ADP |
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518_4_pn_dp_mfp (from the name) | from V3.1.6 | CISA ADP |
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518f_4_pn_dp_mfp (from the name) | from V3.1.6 | CISA ADP |
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP siemens:siplus_s7_1500_cpu_1518_4_pn_dp_mfp (from the name) | from V3.1.6 | CISA ADP |
linux linux_kernel linux:linux_kernel | after 3.13 before 5.10.253; from 5.11 before 5.15.203; from 5.16 before 6.1.168; from 6.2 before 6.6.134; from 6.7 before 6.12.81; from 6.13 before 6.18.22; from 6.19 before 6.19.12; 3.13; and 12 more ranges | NVD |
References
- https://git.kernel.org/stable/c/c438ba010171b70bad22fc18b1d5bdc3627476e8patch
- https://git.kernel.org/stable/c/0452b6526b2f54b2413b9cb4ff1ea2ac542c99c7patch
- https://git.kernel.org/stable/c/a4437faf135da293d16fcc4cc607316742bd0ebbpatch
- https://git.kernel.org/stable/c/3d5127d998de617b130aae96b138dba22ac6a8a7patch
- https://git.kernel.org/stable/c/e41953e7d118e2702bcb217879c173d9d1d3cd4epatch
- https://git.kernel.org/stable/c/a2edbb6393972a02114b6003953a5cef3104fadapatch
- https://git.kernel.org/stable/c/1ceeebd5bd6d855b17a5df625109bfe29129d7cfpatch
- https://git.kernel.org/stable/c/86ab3e55673a7a49a841838776f1ab18d23a67b5patch
- https://access.redhat.com/errata/RHSA-2026:22900
- https://access.redhat.com/errata/RHSA-2026:22940
- https://access.redhat.com/errata/RHSA-2026:22964
- https://access.redhat.com/errata/RHSA-2026:23224
- https://access.redhat.com/errata/RHSA-2026:23237
- https://access.redhat.com/errata/RHSA-2026:24343
- https://access.redhat.com/errata/RHSA-2026:25120
- https://access.redhat.com/errata/RHSA-2026:25121
- https://access.redhat.com/errata/RHSA-2026:25533
- https://access.redhat.com/errata/RHSA-2026:26535
- https://access.redhat.com/errata/RHSA-2026:30129
- https://access.redhat.com/errata/RHSA-2026:30848
- https://access.redhat.com/errata/RHSA-2026:55618
- https://access.redhat.com/errata/RHSA-2026:55761
- https://access.redhat.com/errata/RHSA-2026:55762
- https://access.redhat.com/errata/RHSA-2026:55763
- https://access.redhat.com/errata/RHSA-2026:55837
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.