CVE-2026-128088
Description
A flaw was found in russh. In the Secure Shell (SSH) agent implementation, a signature request made before the agent is locked can still be completed after the lock is engaged because the agent fails to revalidate its lock status following user confirmation. A connected peer or remote server using agent forwarding can initiate a signature request and obtain a valid cryptographic signature even while the agent is locked. This flaw allows an attacker to bypass agent lock protections and perform unauthorized signing operations, although private keys are not exposed.
Statement
This vulnerability is rated as having Low severity because exploitation requires strict timing, active confirmation approval, and cryptographic keys remain protected from disclosure. Core Red Hat Enterprise Linux remote access and authentication stacks utilize OpenSSH rather than the russh library, limiting potential exposure. Any residual risk affects only custom applications embedding this agent implementation where a signing request is already in-flight when the agent is locked.
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 | 2.2 | N/A | 2.2 |
| Attack Vector | Local | N/A | Local |
| Attack Complexity | High | N/A | High |
| Privileges Required | Low | N/A | Low |
| User Interaction | Required | N/A | Required |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | Low | N/A | Low |
| Availability Impact | None | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:N/I:L/A:N
cve.org: CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:N/I:L/A:N
Understanding the Weakness (CWE)
Integrity,Other
Technical Impact: Alter Execution Logic; Unexpected State
The attacker can gain access to otherwise unauthorized resources.
Integrity,Other
Technical Impact: Modify Application Data; Modify Files or Directories; Modify Memory; Other
Race conditions such as this kind may be employed to gain read or write access to resources which are not normally readable or writable by the user in question.
Integrity,Other
Technical Impact: Other
The resource in question, or other resources (through the corrupted one), may be changed in undesirable ways by a malicious user.
Non-Repudiation
Technical Impact: Hide Activities
If a file or other resource is written in this method, as opposed to in a valid way, logging of the activity may not occur.
Non-Repudiation,Other
Technical Impact: Other
In some cases it may be possible to delete files a malicious user might not otherwise have access to, such as log files.
Other
Technical Impact: Unexpected State
The product may perform invalid actions when the resource is in an unexpected state.
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