CVE-2026-63925
Description
A flaw was found in the Linux kernel's MACsec (Media Access Control Security) subsystem. When using Extended Packet Numbering (XPN), a vulnerability exists where the replay protection mechanism can be bypassed. An attacker can exploit an integer overflow when the packet number reaches its maximum value, allowing them to indefinitely replay legitimate MACsec frames. This can lead to a disruption of secure communication and unauthorized re-transmission of data.
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 | 7 | N/A | 8.1 |
| Attack Vector | Local | N/A | Adjacent Network |
| Attack Complexity | High | N/A | Low |
| Privileges Required | Low | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | None |
| Integrity Impact | High | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
Understanding the Weakness (CWE)
Access Control
Technical Impact: Gain Privileges or Assume Identity
Messages sent with a capture-relay attack allow access to resources which are not otherwise accessible without proper authentication.
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