CVE-2026-74683
Description
A flaw was found in the Linux kernel's evdev component. A local user could provide a specially crafted event type index to the EVIOCGMASK or EVIOCSMASK ioctls. This could lead to speculative execution mispredicting bounds checks and performing out-of-bounds loads, potentially resulting in information disclosure.
Statement
This moderate-impact flaw affects the Linux kernel in Red Hat Enterprise Linux and Red Hat In-Vehicle OS. A local user with access to an evdev device could pass a specially crafted event type index to the EVIOCGMASK or EVIOCSMASK ioctls. Although the event type is architecturally bounded by EV_CNT, speculative execution may mispredict the bounds checks and perform out-of-bounds loads when the index is used to access the kernel's internal event mask arrays, potentially resulting in the disclosure of kernel memory contents. Red Hat Enterprise Linux 7, 8, 9, and 10 (kernel and kernel-rt) streams and Red Hat In-Vehicle OS 2 are affected, with the fix deferred to a future update; the deferral reflects the limited practical exploitability of this speculative side channel, and the residual risk is that a local attacker could potentially disclose small amounts of kernel memory. Red Hat Enterprise Linux 6 is out of support scope, so no fix is planned for that stream. Red Hat's moderate rating is lower than the initially suggested high severity because exploitation requires local access with high attack complexity and yields only a limited, side-channel-based disclosure; the Red Hat CVSS:3.1 score (5.5, AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H) additionally weights potential availability impact.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
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).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.5 | N/A | N/A |
| Attack Vector | Local | N/A | N/A |
| Attack Complexity | Low | N/A | N/A |
| Privileges Required | Low | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | None | N/A | N/A |
| Integrity Impact | None | N/A | N/A |
| Availability Impact | High | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Memory
An attacker could get secret values such as cryptographic keys, PII, memory addresses, or other information that could be used in additional attacks.
Confidentiality
Technical Impact: Bypass Protection Mechanism
Out-of-bounds memory could contain memory addresses or other information that can be used to bypass ASLR and other protection mechanisms in order to improve the reliability of exploiting a separate weakness for code execution.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
An attacker could cause a segmentation fault or crash by causing memory to be read outside of the bounds of the buffer. This is especially likely when the code reads a variable amount of data and assumes that a sentinel exists to stop the read operation, such as a NUL in a string.
Other
Technical Impact: Varies by Context
The read operation could produce other undefined or unexpected results.
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