---
title: "CVE-2025-3757: OpenPubkey Vulnerable to Authentication Bypass"
url: https://erroneo.us/security/cve/CVE-2025-3757/
description: "CVE-2025-3757 (github.com/openpubkey/openpubkey (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-2025-3757"
kev: false
cvss: 9.3
epss: 0.00427
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2025-3757: OpenPubkey 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 0.4% , percentile 36: FIRST’s model estimates a 0.4% chance of exploitation activity in the next 30 days, higher than 36% 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/openpubkey (Go) < 0.10.0, fixed in 0.10.0 . 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.

## Affected packages

- Go `github.com/openpubkey/openpubkey` < 0.10.0 → fixed: 0.10.0

## Affected products (CVE record)

- OPKSSH OPKSSH: Openpubkey <= 0.9.0

## 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:L/SC:L/SI:L/SA:L/AU:Y`
- GitHub CVSS 4.0: 9.3 `CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:L/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): 0.43% probability of exploitation activity in the next 30 days; percentile 36.

## Sources

- [GitHub Advisory GHSA-537f-gxgm-3jjq](https://github.com/advisories/GHSA-537f-gxgm-3jjq)
- [CVE.org record CVE-2025-3757](https://www.cve.org/CVERecord?id=CVE-2025-3757)
- [NVD entry CVE-2025-3757](https://nvd.nist.gov/vuln/detail/CVE-2025-3757)
- [github.com](https://github.com/openpubkey/openpubkey)
- [github.com](https://github.com/openpubkey/openpubkey/security/advisories/GHSA-537f-gxgm-3jjq)

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Source page: https://erroneo.us/security/cve/CVE-2025-3757/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt