Junglewise Threat Intelligence

CVE-2026-7598: libssh2 integer overflow in userauth_password

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

Technologies: Libssh2. Vendors: Libssh2.

Executive brief

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.

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

Related threats