CVE-2026-39832
Description
A flaw was found in golang.org/x/crypto/ssh/agent. When a key was added to a remote agent, security restrictions, known as constraint extensions, were not properly processed during the request. This allowed these restrictions to be silently removed when keys were forwarded, leading to the unrestricted use of the key on the remote host. This vulnerability could enable an attacker to bypass intended security controls and perform unauthorized actions.
Statement
This Important vulnerability in golang.org/x/crypto/ssh/agent allows for a security bypass when SSH keys with destination restrictions are forwarded via an SSH agent. This flaw could lead to unintended exposure of SSH keys, enabling an attacker to use the forwarded key without the specified restrictions on remote hosts. Red Hat products utilizing golang.org/x/crypto/ssh/agent for key forwarding may be affected if users rely on constraint extensions for limiting key usage.
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 | 8.7 | N/A | 8.7 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | Low |
| User Interaction | Required | N/A | Required |
| Scope | Changed | N/A | Changed |
| Confidentiality | High | N/A | High |
| Integrity Impact | High | N/A | High |
| Availability Impact | None | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N
Understanding the Weakness (CWE)
Confidentiality,Integrity
Technical Impact: Read Application Data; Modify Application Data
Frequently Asked Questions
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