CVE-2026-56854
Description
A flaw was found in golang.org/x/crypto/ssh. The component failed to properly enforce source-address restrictions for several authentication methods, including password and keyboard-interactive callbacks. In applications that misuse the ServerConfig.PublicKeyCallback callback to make security relevant authorization decisions, an attacker with a valid key could bypass network-based access controls to gain additional privileges.
Statement
This vulnerability severity is Important due to the requirement that an attacker already have a valid private key. A flaw in golang.org/x/crypto/ssh allows remote attackers to bypass source-address restrictions for certain authentication methods. This would allow an attacker to use a valid key for gaining additional privileges outside of the bounds of the network-based access controls.
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).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6.8 | N/A | 7.5 |
| Attack Vector | Network | N/A | 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 | High |
| Integrity Impact | High | N/A | None |
| Availability Impact | None | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Understanding the Weakness (CWE)
Access Control,Other
Technical Impact: Gain Privileges or Assume Identity; Varies by Context
An attacker can access any functionality that is inadvertently accessible to the source.
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