CVE-2026-43099

Analyzed Analyzed - Analysis Complete

Null-Pointer Dereference in Linux Kernel ICMP Probe

Publication date: 2026-05-06

Last updated on: 2026-06-01

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: ipv4: icmp: fix null-ptr-deref in icmp_build_probe() ipv6_stub->ipv6_dev_find() may return ERR_PTR(-EAFNOSUPPORT) when the IPv6 stack is not active (CONFIG_IPV6=m and not loaded), and passing this error pointer to dev_hold() will cause a kernel crash with null-ptr-deref. Instead, silently discard the request. RFC 8335 does not appear to define a specific response for the case where an IPv6 interface identifier is syntactically valid but the implementation cannot perform the lookup at runtime, and silently dropping the request may safer than misreporting "No Such Interface".

CVSS Scores

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Meta Information

Published

2026-05-06

Last Modified

2026-06-01

Generated

2026-07-06

AI Q&A

2026-05-07

EPSS Evaluated

2026-07-05

NVD

CVE-2026-43099

EUVD

EUVD-2026-27608

Affected Vendors & Products

Vendor	Product	Version / Range
linux	linux_kernel	7.0
linux	linux_kernel	7.0
linux	linux_kernel	7.0
linux	linux_kernel	7.0
linux	linux_kernel	7.0
linux	linux_kernel	7.0
linux	linux_kernel	7.0
linux	linux_kernel	From 6.13 (inc) to 6.18.24 (exc)
linux	linux_kernel	From 6.19 (inc) to 6.19.14 (exc)
linux	linux_kernel	From 6.7 (inc) to 6.12.83 (exc)
linux	linux_kernel	From 5.13 (inc) to 6.6.136 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-476	The product dereferences a pointer that it expects to be valid but is NULL.

Attack-Flow Graph

Mitigation Strategies

The vulnerability is resolved by fixing the null pointer dereference in the Linux kernel's ICMP code. Immediate mitigation involves updating the Linux kernel to a version where this fix is applied.

Since the issue occurs when the IPv6 stack is not active (CONFIG_IPV6=m and not loaded), ensuring that the IPv6 stack is either properly enabled or the kernel is updated to handle this case safely can prevent the kernel crash.

Executive Summary

This vulnerability exists in the Linux kernel's handling of certain IPv6 operations. Specifically, when the IPv6 stack is not active (for example, when CONFIG_IPV6 is set to 'm' and the module is not loaded), a function called ipv6_dev_find() may return an error pointer ERR_PTR(-EAFNOSUPPORT). If this error pointer is then passed to another function dev_hold(), it causes a kernel crash due to a null pointer dereference.

The fix involves silently discarding the request instead of passing the error pointer, as the relevant RFC (RFC 8335) does not define a specific response for this scenario. This approach avoids misreporting errors and prevents the kernel crash.

Impact Analysis

This vulnerability can cause the Linux kernel to crash due to a null pointer dereference when handling certain IPv6 interface lookups while the IPv6 stack is inactive. Such a crash can lead to system instability, denial of service, or unexpected reboots, potentially disrupting services running on affected systems.

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