CVE-2026-43502 Linux CVE debrief

Who should care

Linux kernel maintainers, users, and administrators should assess exposure and prioritize patching vulnerable kernel versions. Affected operators, platforms, vulnerability-management, and security teams should review system configurations and kernel versions to determine potential impact and implement necessary mitigations.

Why it matters

A vulnerability in the Linux kernel's RDS subsystem can lead to improper handling of zerocopy send cleanup, potentially causing issues with pinned user pages and message queuing. Linux kernel maintainers and users should assess exposure and prioritize patching vulnerable kernel versions.

• Verify and apply patches to vulnerable kernel versions to prevent potential issues with RDS and zerocopy sends
• Review system configurations and kernel versions to assess exposure
• Monitor system logs for potential issues related to RDS and zerocopy sends

Technical summary

The Linux kernel's RDS subsystem has a vulnerability related to zerocopy send cleanup. When a zerocopy send fails after user pages have been pinned but before the message is attached to the sending socket, the purge path may incorrectly infer zerocopy state. This can lead to improper cleanup of pinned page accounting. The fix captures op_mmp_znotifier upfront in rds_message_purge() and uses it as the cleanup discriminator.

Defensive priority

Linux kernel maintainers and users should assess exposure and prioritize patching vulnerable kernel versions.

Recommended defensive actions

• Assess exposure by reviewing system configurations and kernel versions
• Prioritize patching vulnerable kernel versions
• Monitor system logs for potential issues related to RDS and zerocopy sends
• Review compensating controls for exposed systems while remediation is scheduled and verified
• 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
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and NVD details provide information on the vulnerability, its CVSS score, and affected kernel versions. The fix captures op_mmp_znotifier upfront in rds_message_purge() and uses it as the cleanup discriminator. Evidence is limited to publicly available details from the CVE Program and NVD. Defenders should verify affected kernel versions, review system configurations, and monitor system logs for potential issues related to RDS and zerocopy sends.

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.