CVE-2026-43073 Vulnerability Analysis & Exploit Details

CVE-2026-43073
Vulnerability Scoring

Analysis In Progress

Attack Complexity Details

Attack Complexity:
Attack Complexity Analysis In Progress
Attack Vector:
Attack Vector Under Analysis
Privileges Required: None
No authentication is required for exploitation.
Scope:
Impact is confined to the initially vulnerable component.
User Interaction: None
No user interaction is necessary for exploitation.

CVE-2026-43073 Details

Status: Received on 05 May 2026, 16:16 UTC

Published on: 05 May 2026, 16:16 UTC

CVSS Release:

CVE-2026-43073 Vulnerability Summary

CVE-2026-43073: In the Linux kernel, the following vulnerability has been resolved: x86-64: rename misleadingly named '__copy_user_nocache()' function This function was a masterclass in bad naming, for various historical reasons. It claimed to be a non-cached user copy. It is literally _neither_ of those things. It's a specialty memory copy routine that uses non-temporal stores for the destination (but not the source), and that does exception handling for both source and destination accesses. Also note that while it works for unaligned targets, any unaligned parts (whether at beginning or end) will not use non-temporal stores, since only words and quadwords can be non-temporal on x86. The exception handling means that it _can_ be used for user space accesses, but not on its own - it needs all the normal "start user space access" logic around it. But typically the user space access would be the source, not the non-temporal destination. That was the original intention of this, where the destination was some fragile persistent memory target that needed non-temporal stores in order to catch machine check exceptions synchronously and deal with them gracefully. Thus that non-descriptive name: one use case was to copy from user space into a non-cached kernel buffer. However, the existing users are a mix of that intended use-case, and a couple of random drivers that just did this as a performance tweak. Some of those random drivers then actively misused the user copying version (with STAC/CLAC and all) to do kernel copies without ever even caring about the exception handling, _just_ for the non-temporal destination. Rename it as a first small step to actually make it halfway sane, and change the prototype to be more normal: it doesn't take a user pointer unless the caller has done the proper conversion, and the argument size is the full size_t (it still won't actually copy more than 4GB in one go, but there's also no reason to silently truncate the size argument in the caller). Finally, use this now sanely named function in the NTB code, which mis-used a user copy version (with STAC/CLAC and all) of this interface despite it not actually being a user copy at all.

Assessing the Risk of CVE-2026-43073

Access Complexity Graph

The exploitability of CVE-2026-43073 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).

Exploitability Analysis for CVE-2026-43073

No exploitability data is available for CVE-2026-43073.

Understanding AC and PR

A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.

Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.

Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.

CVSS Score Breakdown Chart

Above is the CVSS Sub-score Breakdown for CVE-2026-43073, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.

CIA Impact Analysis

Below is the Impact Analysis for CVE-2026-43073, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.

Confidentiality: None
CVE-2026-43073 does not compromise confidentiality.
Integrity: None
CVE-2026-43073 does not impact data integrity.
Availability: None
CVE-2026-43073 does not affect system availability.

CVE-2026-43073 References

External References

CWE Common Weakness Enumeration

Unknown

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