GHSA-56wx-66px-9j66 — opkssh
GHSA-56wx-66px-9j66 is a CWE-305 vulnerability in github.com/openpubkey/opkssh. A fix is available for github.com/openpubkey/opkssh — see the affected versions and patch details below.
OPKSSH Vulnerable to Authentication Bypass
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-56wx-66px-9j66.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Real-World Exposure
github.com/openpubkey/opksshReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Impact
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.
Patches
The vulnerability does not exist in more recent versions of OPKSSH. his only impacts OPKSSH when used to verify ssh keys on a server, the OPKSSH client is unaffected. To remediate upgrade to a version of OPKSSH v0.5.0 or greater.
To determine if you are vulnerable run on your server:
opkssh --version
If the version is less than 0.5.0 you should upgrade. To upgrade to the latest version run:
wget -qO- "https://raw.githubusercontent.com/openpubkey/opkssh/main/scripts/install-linux.sh" | sudo bash
References
The upstream vulnerability in OpenPubkey is CVE-2025-3757 and has the security advisory https://github.com/openpubkey/openpubkey/security/advisories/GHSA-537f-gxgm-3jjq
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/openpubkey/opkssh | all versions | 0.5.0go get github.com/openpubkey/opkssh@v0.5.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/openpubkey/opkssh, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/openpubkey/opkssh to 0.5.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-56wx-66px-9j66 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-56wx-66px-9j66 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-56wx-66px-9j66. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-56wx-66px-9j66 in your dependencies?
O3 Security finds GHSA-56wx-66px-9j66 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.