CVE-2026-7598: libssh2 integer overflow in userauth_password

CVE-2026-7598 · Severity: high · CVSS 7.3 · Published 2026-05-01

libssh2 is a widely used library that allows applications to communicate securely using the SSH protocol. A vulnerability was found where a remote attacker could send specially crafted login information to cause an integer overflow. This could lead to application crashes, service disruptions, or potentially unauthorized access to the system.

Technologies: Libssh2. Vendors: Libssh2.

Quick answers

Is CVE-2026-7598 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-7598 being exploited in the wild.
How severe is CVE-2026-7598?
High severity, with a CVSS score of 7.3, published 1 May 2026.
Which products and versions are affected?
Libssh2 up to 1.11.1.
Is there a fix for CVE-2026-7598?
A patch was published on 2026-04-13: Fix merged into libssh2 master branch Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-7598 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-7598?
Check whether you run Libssh2 at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

An integer overflow vulnerability exists in libssh2 versions up to and including 1.11.1 within the userauth_password function in src/userauth.c. The flaw is triggered by improper bounds checking of the username_len and password_len arguments during the SSH authentication process. A remote, unauthenticated attacker can exploit this by providing excessively large length values, leading to a numeric overflow. This can result in memory corruption, a denial-of-service (DoS) condition, or potentially remote code execution. A patch has been released in the upstream repository to enforce strict bounds checking on these variables.

Affected products

  • libssh2 libssh2 up to 1.11.1

Timeline

  • 2026-04-13: patched: Fix merged into libssh2 master branch
  • 2026-05-01: disclosed: Initial vulnerability report published

References

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