Is CVE-2026-43038 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-43038 being exploited in the wild.

How severe is CVE-2026-43038?

Critical severity, with a CVSS score of 9.8, published 1 May 2026.

Which products and versions are affected?

Linux Kernel All versions prior to the April 2026 patches.

Is there a fix for CVE-2026-43038?

A patch was published on 2026-04-18: Patch committed to stable tree Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-43038 attacked?

It is attacked over the network, in an operating system.

Am I affected by CVE-2026-43038?

Check whether you run Linux Kernel at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-43038: Linux Kernel type confusion in ip6_err_gen_icmpv6_unreach

CVE-2026-43038 · Severity: critical · CVSS 9.8 · Published 2026-05-01

A vulnerability was identified in the Linux kernel's networking component that handles communication between different internet protocol versions (IPv4 and IPv6). An attacker could send specially crafted network packets to trigger a memory error, potentially allowing them to crash the system or gain unauthorized access. This affects systems acting as gateways or using specific tunneling protocols like SIT (IPv6 over IPv4).

Technologies: Linux Kernel. Vendors: Linux.

Quick answers

Is CVE-2026-43038 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-43038 being exploited in the wild.
How severe is CVE-2026-43038?: Critical severity, with a CVSS score of 9.8, published 1 May 2026.
Which products and versions are affected?: Linux Kernel All versions prior to the April 2026 patches.
Is there a fix for CVE-2026-43038?: A patch was published on 2026-04-18: Patch committed to stable tree Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-43038 attacked?: It is attacked over the network, in an operating system.
Am I affected by CVE-2026-43038?: Check whether you run Linux Kernel at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A type confusion vulnerability exists in the 'ip6_err_gen_icmpv6_unreach' function within the Linux kernel's IPv6 stack. When an IPv4 ICMP error packet is cloned to generate an ICMPv6 error, the control block (cb) remains populated with IPv4-specific data (inet_skb_parm). The IPv6 stack subsequently interprets this data as an IPv6 control block (inet6_skb_parm). Specifically, the 'cipso' offset from the IPv4 structure overlaps with the 'dsthao' offset in the IPv6 structure. An attacker can provide a forged ICMPv4 packet with a CIPSO option to manipulate the 'dsthao' offset, causing 'mip6_addr_swap' to perform a 16-byte swap at an attacker-controlled offset. This can result in out-of-bounds memory writes into 'skb_shared_info', leading to a system crash or arbitrary code execution. The fix involves zeroing the control block during the conversion process.

Affected products

Linux Linux Kernel All versions prior to the April 2026 patches
Red Hat Enterprise Linux 10.0
Red Hat Enterprise Linux 9.2

Timeline

2026-03-26: disclosed: Initial patch submission by Eric Dumazet
2026-04-18: patched: Patch committed to stable tree
2026-05-01: advisory: CVE-2026-43038 published

References

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