CVE-2019-9155 is a medium-severity (CVSS 5.9) Broken Cryptographic Algorithm 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.
Invalid Curve Attack 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 4.3.0 are vulnerable to an Invalid Curve Attack. The package's implementation of ECDH fails to verify the validity of the communication partner's public key. The package calculates the resulting key secret based on an altered curve instead of the specified elliptic curve. Attackers may exfiltrate the victim's private key by choosing the altered curve. An attack requires the attacker being able to initiate message decryption and record the result. Furthermore the victim's key must offer an ECDH public key.
Recommendation
Upgrade to version 4.3.0 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 | 4.3.0npm install openpgp@4.3.0 |
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 4.3.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2019-9155 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-2019-9155 in your dependencies?
Find it across npm, including transitive dependencies.