CVE-2019-9155 is a medium-severity (CVSS 5.9) Broken Cryptographic Algorithm vulnerability in openpgp. 1 public exploit reference exists, 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
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.
How urgent is this, really
CVE-2019-9155 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,156 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
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 |
Research 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.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2019-9155 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2019-9155. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2019-9155 in your dependencies?
O3 Security finds CVE-2019-9155 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.