CVE-2019-9153 is a high-severity (CVSS 7.5) CWE-347 vulnerability in openpgp. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for openpgp — see the affected versions and patch details below.
Message Signature Bypass in openpgp
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
openpgpnpmDescription
Versions of openpgp prior to 4.2.0 are vulnerable to Message Signature Bypass. The package fails to verify that a message signature is of type text. This allows an attacker to to construct a message with a signature type that only verifies subpackets without additional input (such as standalone or timestamp). For example, an attacker that captures a standalone signature packet from a victim can construct arbitrary signed messages that would be verified correctly.
Recommendation
Upgrade to version 4.2.0 or later.
If you are upgrading from a version <4.0.0 it is highly recommended to read the High-Level API Changes section of the openpgp 4.0.0 release: https://github.com/openpgpjs/openpgpjs/releases/tag/v4.0.0
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | openpgp | all versions | 4.2.0npm install openpgp@4.2.0 |
Affected Products
openpgpjsopenpgpjsResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for openpgp, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update openpgp to 4.2.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2019-9153 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.
Frequently Asked Questions
Is CVE-2019-9153 in your dependencies?
Find it across npm, including transitive dependencies.