# CVE-2026-7598: libssh2 integer overflow in userauth_password

Source: https://junglewise.ai/threats/cve-2026-7598-libssh2-integer-overflow-in-userauth-password  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-01. Updated: 2026-06-30  
License: CC BY 4.0 with a link back

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](https://junglewise.ai/threats/technologies/libssh2). Vendors: [Libssh2](https://junglewise.ai/threats/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

- [https://github.com/libssh2/libssh2/](https://github.com/libssh2/libssh2/)
- [https://github.com/libssh2/libssh2/commit/256d04b60d80bf1190e96b0ad1e91b2174d744b1](https://github.com/libssh2/libssh2/commit/256d04b60d80bf1190e96b0ad1e91b2174d744b1)
- [https://github.com/libssh2/libssh2/pull/1858](https://github.com/libssh2/libssh2/pull/1858)
- [https://vuldb.com/submit/805564](https://vuldb.com/submit/805564)
- [https://vuldb.com/vuln/360555](https://vuldb.com/vuln/360555)
- [https://vuldb.com/vuln/360555/cti](https://vuldb.com/vuln/360555/cti)
- [https://access.redhat.com/errata/RHSA-2026:16736](https://access.redhat.com/errata/RHSA-2026:16736)

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