Linux Kernel
CVE-2024-50102
MEDIUM
Vulnerability Assessment
| Weakness |
CWE
ASVS 5.0
V6 - Authentication Timing-safe comparisons
|
| Impact | CVSS score of 5.5 (MEDIUM). Attack characteristics: local attack vector, low complexity, low privileges required, no user interaction not required. |
| Exploit ScenarioDerived | Successful exploitation could compromise the medium-severity affected system. |
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Alert meAnalysisAI
In the Linux kernel, the following vulnerability has been resolved: x86: fix user address masking non-canonical speculation issue It turns out that AMD has a "Meltdown Lite(tm)" issue with. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity.
RemediationAI
A vendor patch is available. Apply the latest security update as soon as possible. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.
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Technical ContextAI · show details
This vulnerability is classified under CWE-203. In the Linux kernel, the following vulnerability has been resolved: x86: fix user address masking non-canonical speculation issue It turns out that AMD has a "Meltdown Lite(tm)" issue with non-canonical accesses in kernel space. And so using just the high bit to decide whether an access is in user space or kernel space ends up with the good old "leak speculative data" if you have the right gadget using the result: CVE-2020-12965 “Transient Execution of Non-Canonical Accesses“ Now, the kernel surrounds the access with a STAC/CLAC pair, and those instructions end up serializing execution on older Zen architectures, which closes the speculation window. But that was true only up until Zen 5, which renames the AC bit [1]. That improves performance of STAC/CLAC a lot, but also means that the speculation window is now open. Note that this affects not just the new address masking, but also the regular valid_user_address() check used by access_ok(), and the asm version of the sign bit check in the get_user() helpers. It does not affect put_user() or clear_user() variants, since there's no speculative result to be used in a gadget for those operations. Affected products include: Linux Linux Kernel.
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Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
DescriptionNVD
In the Linux kernel, the following vulnerability has been resolved:
x86: fix user address masking non-canonical speculation issue
It turns out that AMD has a "Meltdown Lite(tm)" issue with non-canonical accesses in kernel space. And so using just the high bit to decide whether an access is in user space or kernel space ends up with the good old "leak speculative data" if you have the right gadget using the result:
CVE-2020-12965 “Transient Execution of Non-Canonical Accesses“
Now, the kernel surrounds the access with a STAC/CLAC pair, and those instructions end up serializing execution on older Zen architectures, which closes the speculation window.
But that was true only up until Zen 5, which renames the AC bit [1]. That improves performance of STAC/CLAC a lot, but also means that the speculation window is now open.
Note that this affects not just the new address masking, but also the regular valid_user_address() check used by access_ok(), and the asm version of the sign bit check in the get_user() helpers.
It does not affect put_user() or clear_user() variants, since there's no speculative result to be used in a gadget for those operations.
Threat Intelligence Overview
NVD
CVE.org
EPSS
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.
Affected Products (CPE)NVD
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