CVE-2026-116773
Description
A flaw was found in russh. An unbounded memory allocation issue allows a malicious Secure Shell (SSH) server to cause a Denial of Service (DoS) on connecting clients. By repeatedly sending crafted pre-authentication extension packets, the server forces the client to store an unlimited number of extension entries without clearing or deduplicating them. This behavior leads to progressive memory exhaustion and can crash the client process.
Statement
This vulnerability is rated as Moderate because exploitation requires a client session to connect to an untrusted or rogue SSH server, limiting the impact to client-side resource exhaustion without compromising system confidentiality or integrity. Within Red Hat environments, core operating system services rely on OpenSSH, while russh is only embedded in specialized packages such as openshell. Typical system configurations and standard SSH daemon operations remain completely unaffected by this flaw.
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 | 4.3 | N/A | 4.3 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | Required | N/A | Required |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | Low | N/A | Low |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
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