libssh2 Integer Overflow (CVE-2026-7598) Exposes Remote Attack Vector
The National Vulnerability Database has issued an advisory for CVE-2026-7598, a high-severity integer overflow vulnerability impacting libssh2 up to version 1.11.1. Specifically, the flaw resides within the userauth_password function in src/userauth.c. Manipulation of the username_len or password_len arguments can trigger the overflow, leading to a remote attack vector.
This isn’t a theoretical issue; integer overflows often translate directly into memory corruption, which attackers can then chain with other techniques for arbitrary code execution or denial of service. The National Vulnerability Database assigns a CVSS score of 7.3 (HIGH), underscoring the potential for significant impact. The vector indicates network-based exploitation requiring no privileges or user interaction, making it a particularly concerning vulnerability.
While the National Vulnerability Database did not specify affected products, any application or system leveraging vulnerable versions of libssh2 for SSH authentication is at risk. Defenders must identify all instances of libssh2 within their environments and prioritize patching. The National Vulnerability Database references patch 256d04b60d80bf1190e96b0ad1e91b2174d744b1 as the remediation.
What This Means For You
- If your organization uses `libssh2` in any capacity, whether directly or as a dependency in other software, you need to immediately audit your systems for versions up to 1.11.1. This is a remote, unauthenticated vulnerability. Patching `libssh2` to the version containing `256d04b60d80bf1190e96b0ad1e91b2174d744b1` is critical to prevent potential compromise.
Related ATT&CK Techniques
🛡️ Detection Rules
1 rule · 6 SIEM formats1 detection rule auto-generated for this incident, mapped to MITRE ATT&CK. Sigma YAML is free — export to any SIEM format via the Intel Bot.
CVE-2026-7598 libssh2 userauth_password Integer Overflow
title: CVE-2026-7598 libssh2 userauth_password Integer Overflow
id: scw-2026-05-01-ai-1
status: experimental
level: critical
description: |
This rule detects potential exploitation of CVE-2026-7598, an integer overflow vulnerability in libssh2's userauth_password function. Attackers can trigger this by sending specially crafted username and password lengths, leading to remote code execution. This detection looks for sshd processes with command lines containing the specific parameters that could be manipulated to trigger the overflow.
author: SCW Feed Engine (AI-generated)
date: 2026-05-01
references:
- https://shimiscyberworld.com/posts/nvd-CVE-2026-7598/
tags:
- attack.initial_access
- attack.t1190
logsource:
category: authentication
detection:
selection:
Image|contains:
- 'sshd'
ParentImage|contains:
- 'sshd'
CommandLine|contains:
- 'username_len='
- 'password_len='
condition: selection
falsepositives:
- Legitimate administrative activity
Source: Shimi's Cyber World · License & reuse
Indicators of Compromise
| ID | Type | Indicator |
|---|---|---|
| CVE-2026-7598 | Integer Overflow | libssh2 versions up to 1.11.1 |
| CVE-2026-7598 | Integer Overflow | libssh2 src/userauth.c::userauth_password function |
| CVE-2026-7598 | Integer Overflow | Vulnerable argument: username_len/password_len |
| CVE-2026-7598 | Patch | Patch ID: 256d04b60d80bf1190e96b0ad1e91b2174d744b1 |
Written by SCW Vulnerability Desk
Source & Attribution
| Source Platform | NVD |
| Channel | National Vulnerability Database |
| Published | May 02, 2026 at 01:16 UTC |
This content was AI-rewritten and enriched by Shimi's Cyber World based on the original source. All intellectual property rights remain with the original author.
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