CVE-2021-25915 is a critical-severity (CVSS 9.8) CWE-1321 vulnerability in changeset. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for changeset — see the affected versions and patch details below.
Changeset vulnerable to prototype pollution
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA’s SSVC triage for CVE-2021-25915.
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.
changesetnpmDescription
Overview
Prototype pollution vulnerability in 'changeset' versions 0.0.1 through 0.2.5 allows attackers to cause a denial of service and may lead to remote code execution.
Details
The npm module 'changeset' can be abused by Prototype Pollution vulnerability since the function 'apply()' does not check for the type of object before assigning value to the property. Due to this flaw an attacker could create a non-existent property or able to manipulate the property which leads to Denial of Service or potentially Remote code execution.
PoC Details
The 'apply()' function accepts 'changes, target, modify' as argument. Due to the absence of validation on the values passed into the 'changes' argument, an attacker can supply a malicious value by adjusting the value to include the 'proto' property. Since there is no validation before assigning the property to check whether the assigned argument is the Object's own property or not, the property 'polluted' will be directly be assigned to the new object thereby polluting the Object prototype. Using the example below, if there is a check to validate 'polluted' the valued later in the code, it would be substituted as "Yes! Its Polluted" as it had been polluted.
PoC Code
var changeset = require("changeset") const patch = [{
type: 'put',
key: ["__proto__", "polluted"],
value: "Yes! Its Polluted"
}];
console.log("Before : " + {}.polluted);
changeset.apply(patch, {}, true);
console.log("After : " + {}.polluted);
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | changeset | ≥ 0.0.1&&< 0.2.5 | 0.2.5npm install changeset@0.2.5 |
Affected Products
changesetchangeset_projectResearch 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 changeset, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update changeset to 0.2.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-25915 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
Frequently Asked Questions
Is CVE-2021-25915 in your dependencies?
Find it across npm, including transitive dependencies.