# CVE-2026-59842: Libssh: libssh: information disclosure via short gssapi curve25519 public key

> A remote unauthenticated attacker can disclose small amounts of server memory via an out-of-bounds heap read during GSSAPI key exchange in libssh.

- **Severity:** Low 3.7 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 21 Jul 2026
- **Updated:** 19 Aug 2026
- **Also known as:** BELL-CVE-2026-59842, DEBIAN-CVE-2026-59842, GHSA-x94w-cg8g-g593, MINI-c4mg-2422-vx22

## What is CVE-2026-59842?

CVE-2026-59842 is a low-severity vulnerability in Redhat Enterprise Linux, published on 21 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A flaw was found in libssh. During server-side GSSAPI key exchange, a client-supplied Curve25519 public key shorter than the expected length is copied without proper length validation, leading to an out-of-bounds heap read. This could allow a remote unauthenticated attacker to disclose small amounts of server memory.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-59842?

It affects 11 products.


Products: Libssh Libssh, Redhat Enterprise Linux, Redhat Enterprise Linux for Els, Redhat Enterprise Linux for Eus, Redhat Enterprise Linux for Ibm Z Systems, Redhat Enterprise Linux for Ibm Z Systems Els, Redhat Enterprise Linux for Ibm Z Systems Eus, Redhat Enterprise Linux for Power Little Endian, Redhat Enterprise Linux for Power Little Endian Els, Redhat Enterprise Linux for Power Little Endian Eus, Redhat Hardened Images.

## How do I fix CVE-2026-59842?

Apply the vendor's patch.

## Is CVE-2026-59842 being exploited?

There is no known exploitation of CVE-2026-59842 in the wild and no public exploit code.

## Other vulnerabilities in Redhat Enterprise Linux

- [CVE-2026-59851](https://insights.sbomify.com/CVE-2026-59851/): Libssh: libssh: authentication bypass via missing gssapi principal check (high 8.8)
- [CVE-2025-5987](https://insights.sbomify.com/CVE-2025-5987/): Libssh: invalid return code for chacha20 poly1305 with openssl backend (high 8.1)
- [CVE-2025-14821](https://insights.sbomify.com/CVE-2025-14821/): Libssh: libssh: insecure default configuration leads to local man-in-the-middle attacks on windows (high 7.8)
- [CVE-2012-4560](https://insights.sbomify.com/CVE-2012-4560/): Memory corruption in n/a (high 7.5)
- [CVE-2012-4562](https://insights.sbomify.com/CVE-2012-4562/): Integer overflow in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-59842 and fix it if it is affected.

What it is: CVE-2026-59842 is a low-severity vulnerability in Redhat Enterprise Linux, published on 21 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-59842 in the wild and no public exploit code.

Affected product: Redhat Enterprise Linux. 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-2026-59842/ (Markdown: https://insights.sbomify.com/CVE-2026-59842/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-59842
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-59842
- OSV: https://osv.dev/vulnerability/CVE-2026-59842

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-59842/
Summaries are generated and may contain mistakes; the official description above is the record.