CVE-2026-66035
7.5 · HIGHOverview
CVE-2026-66035 is a high-severity vulnerability affecting libssh2 libssh2. It was published on July 24, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).
This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
libssh2 through 1.11.1, fixed in commit 42e33d8, contains a pre-authentication heap buffer overflow vulnerability that allows a malicious SSH server to corrupt heap metadata in any connecting client by sending a packet with a packet_length smaller than the cipher's block size during Encrypt-then-MAC cipher negotiation. In the fullpacket() function in src/transport.c, the ETM path allocates a buffer of packet_length bytes but copies blocksize minus one bytes via memcpy, causing an overflow that on 32-bit glibc writes attacker-controlled bytes into an adjacent chunk's SIZE field, enabling tcache bin confusion, overlapping live objects, and function pointer overwrite during the session handshake before authentication.
Remediation
Check the references section for vendor advisories and patches from libssh2. Update libssh2 to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| libssh2 | libssh2 | 0 | Affected |
Frequently Asked Questions
What is CVE-2026-66035?
CVE-2026-66035 is a high-severity vulnerability affecting libssh2 libssh2. It was published on July 24, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).
How severe is CVE-2026-66035?
This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2026-66035?
Check the references section for vendor advisories and patches from libssh2. Update libssh2 to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-66035?
CyberStrike's AI-powered security agents can automatically detect CVE-2026-66035 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
Automated penetration testing that runs continuously, not just quarterly.
AI-driven PR review catches vulnerable dependencies before they ship.
Browser-based exploitation validates findings with real proof-of-concept.
Related HIGH CVEs from 2026
View all →H3 is a minimal H(TTP) framework built for high performance and portability. Prior to 1.15.5, there
OpenProject is an open-source, web-based project management software. To enable the real time collab
OpenSift is an AI study tool that sifts through large datasets using semantic search and generative
Budibase is a low code platform for creating internal tools, workflows, and admin panels. In 3.24.0
FileBrowser Quantum is a free, self-hosted, web-based file manager. Prior to 1.3.1-beta and 1.2.2-st
Shopware is an open commerce platform. Prior to 6.6.10.15 and 6.7.8.1, a vulnerability in the Shopwa
ChurchCRM is an open-source church management system. Prior to 7.1.0, a stored cross-site scripting
A Stored Cross-Site Scripting vulnerability was discovered in the Assets and Nodes functionality due
Postiz is an AI social media scheduling tool. Prior to version 2.21.6, a file upload validation bypa
A server-side request forgery (SSRF) vulnerability was identified in GitHub Enterprise Server that a
Cross-Site Scripting (XSS) vulnerability exists in HTMLy version 3.1.1 in the content creation funct
An Improper Certificate Validation in Ivanti EPMM before versions 12.6.1.1, 12.7.0.1, and 12.8.0.1 a