CVE-2026-64368 Linux CVE debrief

Who should care

Linux kernel developers and maintainers who need to assess exposure and verify affected versions. They should review the Linux kernel's mm/slab implementation, assess potential security consequences, and verify the fix in the Linux kernel source code. Additionally, they should monitor for potential impact on krealloc() __GFP_ZERO contract and document findings and remediation steps.

Why it matters

A vulnerability in the Linux kernel's mm/slab implementation can cause a compromise of the krealloc() __GFP_ZERO contract when red zoning is enabled but the requested size is not tracked. Linux kernel developers and maintainers should assess exposure and verify affected versions.

• Verify affected Linux kernel versions
• Assess potential impact on krealloc() __GFP_ZERO contract
• Monitor for potential security consequences

Technical summary

The Linux kernel's mm/slab implementation has a vulnerability that can cause a compromise of the krealloc() __GFP_ZERO contract when red zoning is enabled but the requested size is not tracked. This issue is resolved by using slub_debug_orig_size() to accurately check if the requested size is tracked. The vulnerability arises from the current check being imprecise, triggering also when only SLAB_RED_ZONE is enabled without SLAB_STORE_USER. The fix ensures that the krealloc() __GFP_ZERO contract is not compromised when red zoning is enabled.

Defensive priority

High

Recommended defensive actions

• Review Linux kernel versions and assess exposure
• Verify affected versions using official Linux kernel sources
• Monitor for potential impact on krealloc() __GFP_ZERO contract
• Perform a thorough review of the Linux kernel's mm/slab implementation
• Assess potential security consequences
• Verify the fix in the Linux kernel source code
• Document findings and remediation steps

Evidence notes

The CVE record and source item provide details on the vulnerability, but the scope of affected versions and potential impact require further verification from official Linux kernel sources. The issue is resolved by using slub_debug_orig_size() instead of the current imprecise check. This change ensures that the krealloc() __GFP_ZERO contract is not compromised when red zoning is enabled. Linux kernel developers and maintainers should verify affected versions and assess potential impact.

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.