CVE-2026-55200

Analyzed Analyzed - Analysis Complete

libssh2 Out-of-Bounds Write in ssh2_transport_read

Publication date: 2026-06-17

Last updated on: 2026-07-01

Assigner: VulnCheck

Description

libssh2 through 1.11.1, fixed in commit 7acf3df contains an out-of-bounds write vulnerability in ssh2_transport_read() that fails to enforce upper bounds on packet_length field. Remote attackers can send crafted SSH packets with excessively large packet_length values to corrupt heap memory and achieve remote code execution.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published

2026-06-17

Last Modified

2026-07-01

Generated

2026-07-08

AI Q&A

2026-06-18

EPSS Evaluated

2026-07-06

NVD

CVE-2026-55200

EUVD

EUVD-2026-37784

Affected Vendors & Products

Vendor	Product	Version / Range
libssh2	libssh2	to 1.11.1 (inc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-680	The product performs a calculation to determine how much memory to allocate, but an integer overflow can occur that causes less memory to be allocated than expected, leading to a buffer overflow.

Attack-Flow Graph

Executive Summary

This vulnerability exists in libssh2 versions up to 1.11.1 in the function ssh2_transport_read(). It is caused by a failure to enforce upper bounds on the packet_length field, which allows remote attackers to send specially crafted SSH packets with excessively large packet_length values.

This leads to an out-of-bounds write that can corrupt heap memory.

As a result, attackers can achieve remote code execution on the affected system.

Impact Analysis

The vulnerability can have severe impacts including allowing remote attackers to execute arbitrary code on your system without any user interaction or privileges.

This can lead to full system compromise, data theft, disruption of services, or further attacks within your network.

Hi! I’m here to help you understand CVE-2026-55200. Ask me anything about the vulnerability, its impact, or mitigation strategies.

0/70