# CVE-2026-58050: libssh2 - Integer Overflow in publickey Subsystem Attribute Allocation

> A malicious SSH server can trigger an integer overflow in libssh2 clients, leading to a heap buffer overflow and potential code execution.

- **Severity:** High 8.3 (`CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 28 Jun 2026
- **Updated:** 29 Jun 2026
- **Also known as:** ALPINE-CVE-2026-58050, AZL-97407, AZL-97434, BELL-CVE-2026-58050, CLSA-2026-1783634800, CLSA-2026-1783635077, CLSA-2026-1784069784, CLSA-2026-1784069914, CLSA-2026-1784069953, CLSA-2026-1784070060, CLSA-2026-1784282780, CLSA-2026-1785308535, DEBIAN-CVE-2026-58050, GHSA-mf77-5hj2-98w9, JLSEC-2026-662, RHSA-2026:54070, UBUNTU-CVE-2026-58050

## What is CVE-2026-58050?

CVE-2026-58050 is a high-severity vulnerability in libssh2, published on 28 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

libssh2 through 1.11.1 reads an attacker-controlled 32-bit attribute count from a publickey-subsystem response and uses it in the allocation num_attrs * sizeof(libssh2_publickey_attribute) without bounds checking, so on 32-bit platforms the multiplication overflows to an undersized buffer. A malicious SSH server can then drive the attribute-parsing loop to write past the allocation, causing a heap buffer overflow in a connecting libssh2 client.

Weakness: CWE-190 (Integer Overflow or Wraparound)

## Which versions are affected by CVE-2026-58050?

It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `libssh2` | Red Hat:hummingbird:1 | All versions | 0:1.11.1-10.4.hum1 |
| `libssh2-devel` | Red Hat:hummingbird:1 | All versions | 0:1.11.1-10.4.hum1 |
| `libssh2-docs` | Red Hat:hummingbird:1 | All versions | 0:1.11.1-10.4.hum1 |

Products: Libssh2 Libssh2.

## How do I fix CVE-2026-58050?

Upgrade to a fixed version.

## Is CVE-2026-58050 being exploited?

There is no known exploitation of CVE-2026-58050 in the wild and no public exploit code.

## 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-2026-58051](https://insights.sbomify.com/CVE-2026-58051/): libssh2 - Free of Uninitialized Pointer in publickey List Cleanup (high 8.3)
- [CVE-2025-15661](https://insights.sbomify.com/CVE-2025-15661/): libssh2 - Heap Buffer Over-read via sftp_symlink() in sftp.c (high 8.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-58050 and fix it if it is affected.

What it is: CVE-2026-58050 is a high-severity vulnerability in libssh2, published on 28 Jun 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-2026-58050 in the wild and no public exploit code.

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-2026-58050/ (Markdown: https://insights.sbomify.com/CVE-2026-58050/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-58050
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-58050
- OSV: https://osv.dev/vulnerability/CVE-2026-58050

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-58050/
Summaries are generated and may contain mistakes; the official description above is the record.