CVE-2026-23156
Description
A flaw was found in the efivarfs component of the Linux kernel. This vulnerability, an information disclosure issue, arises from incorrect error handling in the efivar_entry_get function. An unprivileged local attacker can exploit this by reading from efivarfs, potentially causing uninitialized kernel memory to be copied to userspace. This could allow the attacker to obtain sensitive kernel memory contents, which may aid in bypassing security mitigations.
Statement
A local information disclosure issue exists in efivarfs due to incorrect error propagation in efivar_entry_get. The wrapper efivar_entry_get called __efivar_entry_get to retrieve EFI variable data but always returned success 0 even when the underlying function failed. This causes callers to treat the output buffers attributes size and data as valid even though the read may not have completed. In the efivarfs file read path efivarfs_file_read this can result in copying an uninitialized or partially initialized kernel heap buffer to userspace. An unprivileged local attacker who can read from efivarfs can potentially obtain kernel memory contents. Such leaks can expose sensitive information and may be useful to bypass mitigations such as KASLR in combination with other vulnerabilities.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.3 | 7.8 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | Low | Low | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | High | High | N/A |
| Integrity Impact | Low | High | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H
NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Integrity,Other
Technical Impact: Varies by Context; Unexpected State; Alter Execution Logic
An attacker could utilize an ignored error condition to place the system in an unexpected state that could lead to the execution of unintended logic and could cause other unintended behavior.
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