GHSA-j658-c2gf-x6pq — velocityjs
HIGHGHSA-j658-c2gf-x6pq is a high-severity (CVSS 8.3) CWE-1321 vulnerability in velocityjs. No vendor fix is recorded yet; mitigation options are listed below.
Velocity.js has a Prototype Pollution vulnerability through #set path assignment
Exploitation Status
No confirmed exploitation observed yet
- 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-j658-c2gf-x6pq.
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
GHSA-j658-c2gf-x6pq 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 377,166 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.
velocityjsnpmDescription
Summary
A prototype pollution vulnerability was discovered in Velocity.js <= 2.1.5. This issue occurs during the processing of #set directives in Velocity templates. If an application renders a template controlled by an attacker, it is possible to modify Object.prototype, potentially leading to Denial of Service (DoS) or Remote Code Execution (RCE) depending on the server environment.
Details
The root cause is located in the #set path assignment logic within the source code:
- File: /src/compile/set.ts
- Issue: The engine accepts arbitrary path keys and performs assignments using the logic
(baseRef as Record<string, unknown>)[key] = val.
Because there is no validation or filtering to block sensitive keys such as __proto__, constructor, or prototype, an attacker can traverse the prototype chain and pollute the global Object.prototype.
PoC
const {render} = require('velocityjs');
delete Object.prototype.polluted;
console.log({}.polluted); // ""
render('#set($__proto__.polluted = "hacked")', {});
console.log({}.polluted); // "hacked"
delete Object.prototype.polluted;
Impact
- Vulnerability Type: Prototype Pollution
- Who is impacted: Any application that renders Velocity templates where the template content can be influenced or controlled by untrusted users.
- Severity: High. Prototype pollution can often be used to bypass security controls, cause application crashes (DoS), or be chained with other vulnerabilities to achieve code execution.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | velocityjs | all versions | No fix |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for velocityjs, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Remediation status
No patched version of velocityjs has shipped for GHSA-j658-c2gf-x6pq yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
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-j658-c2gf-x6pq can be triaged on real exposure rather than presence alone.
Tailored to GHSA-j658-c2gf-x6pq. 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-j658-c2gf-x6pq in your dependencies?
O3 Security finds GHSA-j658-c2gf-x6pq across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.