# CVE-2026-7598: libssh2 userauth.c userauth_password integer overflow

> A remote attacker can trigger an integer overflow in libssh2's password authentication, potentially causing a denial of service.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:X`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 1 May 2026
- **Updated:** 1 Sep 2026
- **Also known as:** ALPINE-CVE-2026-7598, AZL-85451, AZL-97404, AZL-97431, BELL-CVE-2026-7598, CLSA-2026-1778247114, CLSA-2026-1778602690, CLSA-2026-1778602853, CLSA-2026-1778745959, CLSA-2026-1778895374, CLSA-2026-1779216196, DEBIAN-CVE-2026-7598, ECHO-e686-bef9-6a8e, GHSA-jhp3-h4hp-2c3p, JLSEC-2026-492, MINI-x2fh-58wp-gxgc, OESA-2026-2336, RHSA-2026:16736, RHSA-2026:7021, ROOT-OS-DEBIAN-11-CVE-2026-7598, UBUNTU-CVE-2026-7598, USN-8309-1

## What is CVE-2026-7598?

CVE-2026-7598 is a medium-severity vulnerability in libssh2, published on 1 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A security vulnerability has been detected in libssh2 up to 1.11.1. The impacted element is the function userauth_password of the file src/userauth.c. Such manipulation of the argument username_len/password_len leads to integer overflow. The attack may be launched remotely. The name of the patch is 256d04b60d80bf1190e96b0ad1e91b2174d744b1. A patch should be applied to remediate this issue.

Weakness: CWE-190 (Integer Overflow or Wraparound), CWE-189

## Which versions are affected by CVE-2026-7598?

It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `libssh2` | Red Hat:hummingbird:1 | All versions | 0:1.11.1-5.1.hum1 |
| `libssh2-devel` | Red Hat:hummingbird:1 | All versions | 0:1.11.1-5.1.hum1 |
| `libssh2-docs` | Red Hat:hummingbird:1 | All versions | 0:1.11.1-5.1.hum1 |
| `rust` | Red Hat:hummingbird:1 | All versions | 0:1.95.0-5.hum1 |
| `rust-analyzer` | Red Hat:hummingbird:1 | All versions | 0:1.95.0-5.hum1 |
| `rust-debugger-common` | Red Hat:hummingbird:1 | All versions | 0:1.95.0-5.hum1 |
| `rust-doc` | Red Hat:hummingbird:1 | All versions | 0:1.95.0-5.hum1 |
| `rust-gdb` | Red Hat:hummingbird:1 | All versions | 0:1.95.0-5.hum1 |
| `rust-lldb` | Red Hat:hummingbird:1 | All versions | 0:1.95.0-5.hum1 |
| `rust-src` | Red Hat:hummingbird:1 | All versions | 0:1.95.0-5.hum1 |
| `rust-std-static` | Red Hat:hummingbird:1 | All versions | 0:1.95.0-5.hum1 |
| `rust-std-static-aarch64-unknown-none-softfloat` | Red Hat:hummingbird:1 | All versions | 0:1.95.0-5.hum1 |
| `rust-std-static-aarch64-unknown-uefi` | Red Hat:hummingbird:1 | All versions | 0:1.95.0-5.hum1 |
| `rust-std-static-i686-pc-windows-gnu` | Red Hat:hummingbird:1 | All versions | 0:1.95.0-5.hum1 |
| `rust-std-static-wasm32-unknown-unknown` | Red Hat:hummingbird:1 | All versions | 0:1.95.0-5.hum1 |
| `rust-std-static-wasm32-wasip1` | Red Hat:hummingbird:1 | All versions | 0:1.95.0-5.hum1 |
| `rust-std-static-x86_64-pc-windows-gnu` | Red Hat:hummingbird:1 | All versions | 0:1.95.0-5.hum1 |
| `rust-std-static-x86_64-unknown-none` | Red Hat:hummingbird:1 | All versions | 0:1.95.0-5.hum1 |
| `rust-std-static-x86_64-unknown-uefi` | Red Hat:hummingbird:1 | All versions | 0:1.95.0-5.hum1 |
| `rustfmt` | Red Hat:hummingbird:1 | All versions | 0:1.95.0-5.hum1 |

Products: Libssh2 Libssh2.

## How do I fix CVE-2026-7598?

Apply the vendor's patch.

## Is CVE-2026-7598 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-7598 exists.

## Other vulnerabilities in libssh2

- [CVE-2026-55200](https://insights.sbomify.com/CVE-2026-55200/): libssh2 - Out-of-Bounds Write via Unchecked packet_length in transport.c (critical 9.2)
- [CVE-2026-66032](https://insights.sbomify.com/CVE-2026-66032/): libssh2 Double-Free Heap Corruption via sftp_open() (high 8.7)
- [CVE-2026-66033](https://insights.sbomify.com/CVE-2026-66033/): libssh2 Integer Underflow DoS via AES-GCM Cipher Negotiation (high 8.7)
- [CVE-2026-58050](https://insights.sbomify.com/CVE-2026-58050/): libssh2 - Integer Overflow in publickey Subsystem Attribute Allocation (high 8.3)
- [CVE-2026-58051](https://insights.sbomify.com/CVE-2026-58051/): libssh2 - Free of Uninitialized Pointer in publickey List Cleanup (high 8.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-7598 and fix it if it is affected.

What it is: CVE-2026-7598 is a medium-severity vulnerability in libssh2, published on 1 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-7598 exists.

Affected product: libssh2. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-7598/ (Markdown: https://insights.sbomify.com/CVE-2026-7598/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-7598
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-7598
- OSV: https://osv.dev/vulnerability/CVE-2026-7598

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-7598/
Summaries are generated and may contain mistakes; the official description above is the record.