---
title: "CVE-2025-4658: OPKSSH Vulnerable to Authentication Bypass"
url: https://erroneo.us/security/cve/CVE-2025-4658/
description: "CVE-2025-4658 (github.com/openpubkey/opkssh (Go)): Versions of OpenPubkey library prior to 0.10.0 contained a vulnerability that would allow a specially…"
type: vulnerability-record
section: "Security Digest"
date_published: 2025-05-13
date_modified: 2025-05-13
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2025-4658"
kev: false
cvss: 9.3
epss: 0.0034
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2025-4658: OPKSSH Vulnerable to Authentication Bypass

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 0.3% , percentile 26: FIRST’s model estimates a 0.3% chance of exploitation activity in the next 30 days, higher than 26% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes github.com/openpubkey/opkssh (Go) < 0.5.0, fixed in 0.5.0 . Check your lockfile, including transitive dependencies.

## What it is

Versions of OpenPubkey library prior to 0.10.0 contained a vulnerability that would allow a specially crafted JWS to bypass signature verification. As OPKSSH depends on the OpenPubkey library for authentication, this vulnerability in OpenPubkey also applies to OPKSSH versions prior to 0.5.0 and would allow an attacker to bypass OPKSSH authentication.

## Affected packages

- Go `github.com/openpubkey/opkssh` < 0.5.0 → fixed: 0.5.0

## Affected products (CVE record)

- OPKSSH OPKSSH: 0.1.0 <= 0.4.0

## Severity

- cloudflare CVSS 4.0: 9.3 `CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:L`
- GitHub CVSS 4.0: 9.3 `CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:L`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.34% probability of exploitation activity in the next 30 days; percentile 26.

## Sources

- [GitHub Advisory GHSA-56wx-66px-9j66](https://github.com/advisories/GHSA-56wx-66px-9j66)
- [CVE.org record CVE-2025-4658](https://www.cve.org/CVERecord?id=CVE-2025-4658)
- [NVD entry CVE-2025-4658](https://nvd.nist.gov/vuln/detail/CVE-2025-4658)
- [github.com](https://github.com/openpubkey/opkssh)
- [github.com](https://github.com/openpubkey/opkssh/security/advisories/GHSA-56wx-66px-9j66)

---
Source page: https://erroneo.us/security/cve/CVE-2025-4658/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt