CVE-2026-58051
Description
A flaw in libssh2 allows a malicious SSH server to send a malformed public key response, triggering an invalid memory cleanup. This can cause the connecting client application to crash or leak information.
Statement
Moderate: This flaw in libssh2 can lead to a denial of service or information disclosure in client applications when connecting to a malicious SSH server. The vulnerability arises from improper handling of uninitialized memory during public key list processing, which an attacker can trigger with a specially crafted response. Exploitation requires active interaction with a compromised or malicious server, limiting the attack surface to untrusted connections.
Note: Red Hat Enterprise Linux (RHEL) 8 and newer are not affected by this flaw, as they do not ship the libssh2 package.
Mitigation
To mitigate this issue, ensure your applications connect only to trusted and verified SSH servers. For added protection, maintain standard system memory defenses to automatically intercept and safely terminate any processes corrupted by an unexpected server error.
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 | 6.5 | N/A | 6.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | High | N/A | High |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | Low | N/A | None |
| Integrity Impact | None | N/A | Low |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Memory
If the uninitialized pointer is used in a read operation, an attacker might be able to read sensitive portions of memory.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
If the uninitialized pointer references a memory location that is not accessible to the product, or points to a location that is "malformed" (such as NULL) or larger than expected by a read or write operation, then a crash may occur.
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
If the uninitialized pointer is used in a function call, or points to unexpected data in a write operation, then code execution may be possible.
Frequently Asked Questions
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