CVE-2026-45846 Linux CVE debrief

Who should care

Linux kernel maintainers, Linux distribution maintainers, and users of Linux kernel versions affected by this vulnerability. These individuals should apply patches to prevent this vulnerability and assess the exposure of their Linux kernel deployments. They should also monitor Linux kernel updates for potential future vulnerabilities and verify Linux kernel versions to ensure patched versions are used.

Why it matters

This vulnerability in the Linux kernel can cause a NULL pointer dereference when the bareudp_fill_metadata_dst() function is called while the device is down. Linux kernel maintainers and users should apply patches to prevent this vulnerability.

• Verify Linux kernel versions and apply patches to prevent NULL pointer dereferences
• Monitor Linux kernel updates for potential future vulnerabilities
• Assess exposure of Linux kernel deployments to this vulnerability

Technical summary

The Linux kernel's bareudp_fill_metadata_dst() function did not check for NULL before calling udp_tunnel6_dst_lookup(). This led to a NULL pointer dereference when the device was down. A fix has been applied to return -ESHUTDOWN in such cases. The affected product is the Linux kernel, specifically the bareudp module. The vulnerability is a NULL pointer dereference, which can cause a system crash or potentially allow an attacker to execute arbitrary code. The fix involves adding a NULL check to prevent the NULL pointer dereference.

Defensive priority

Medium priority for Linux kernel maintainers and users to apply patches

Recommended defensive actions

• Apply patches provided by Linux kernel maintainers
• Review and update Linux kernel versions to ensure patched versions are used
• Monitor Linux kernel updates for potential future vulnerabilities
• Verify Linux kernel versions and apply patches to prevent NULL pointer dereferences
• Assess exposure of Linux kernel deployments to this vulnerability
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The vulnerability was reported in the Linux kernel and resolved by adding a NULL check. The CVE record and NVD entry provide details on the vulnerability. The Linux kernel maintainers and users should verify the affected scope and apply patches to prevent this vulnerability. The vulnerability is a NULL pointer dereference, which can cause a system crash or potentially allow an attacker to execute arbitrary code.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.