GHSA-qm95-pgcg-qqfq is a critical-severity (CVSS 9.8) SQL Injection vulnerability in socket.io-parser. A fix is available for socket.io-parser — see the affected versions and patch details below.
Insufficient validation when decoding a Socket.IO packet
Exploitation Status
No confirmed exploitation observed yet
- 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.
- 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-qm95-pgcg-qqfq.
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-qm95-pgcg-qqfq 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.
socket.io-parsernpmDescription
Due to improper type validation in the socket.io-parser library (which is used by the socket.io and socket.io-client packages to encode and decode Socket.IO packets), it is possible to overwrite the _placeholder object which allows an attacker to place references to functions at arbitrary places in the resulting query object.
Example:
const decoder = new Decoder();
decoder.on("decoded", (packet) => {
console.log(packet.data); // prints [ 'hello', [Function: splice] ]
})
decoder.add('51-["hello",{"_placeholder":true,"num":"splice"}]');
decoder.add(Buffer.from("world"));
This bubbles up in the socket.io package:
io.on("connection", (socket) => {
socket.on("hello", (val) => {
// here, "val" could be a function instead of a buffer
});
});
:warning: IMPORTANT NOTE :warning:
You need to make sure that the payload that you received from the client is actually a Buffer object:
io.on("connection", (socket) => {
socket.on("hello", (val) => {
if (!Buffer.isBuffer(val)) {
socket.disconnect();
return;
}
// ...
});
});
If that's already the case, then you are not impacted by this issue, and there is no way an attacker could make your server crash (or escalate privileges, ...).
Example of values that could be sent by a malicious user:
- a number that is out of bounds
Sample packet: 451-["hello",{"_placeholder":true,"num":10}]
io.on("connection", (socket) => {
socket.on("hello", (val) => {
// val is `undefined`
});
});
- a value that is not a number, like
undefined
Sample packet: 451-["hello",{"_placeholder":true,"num":undefined}]
io.on("connection", (socket) => {
socket.on("hello", (val) => {
// val is `undefined`
});
});
- a string that is part of the prototype of
Array, like "push"
Sample packet: 451-["hello",{"_placeholder":true,"num":"push"}]
io.on("connection", (socket) => {
socket.on("hello", (val) => {
// val is a reference to the "push" function
});
});
- a string that is part of the prototype of
Object, like "hasOwnProperty"
Sample packet: 451-["hello",{"_placeholder":true,"num":"hasOwnProperty"}]
io.on("connection", (socket) => {
socket.on("hello", (val) => {
// val is a reference to the "hasOwnProperty" function
});
});
This should be fixed by:
- https://github.com/socketio/socket.io-parser/commit/b5d0cb7dc56a0601a09b056beaeeb0e43b160050, included in
[email protected] - https://github.com/socketio/socket.io-parser/commit/b559f050ee02bd90bd853b9823f8de7fa94a80d4, included in
[email protected] - https://github.com/socketio/socket.io-parser/commit/04d23cecafe1b859fb03e0cbf6ba3b74dff56d14, included in
[email protected] - https://github.com/socketio/socket.io-parser/commit/fb21e422fc193b34347395a33e0f625bebc09983, included in
[email protected]
Dependency analysis for the socket.io package
socket.io version | socket.io-parser version | Covered? |
|---|---|---|
4.5.2...latest | ~4.2.0 (ref) | Yes :heavy_check_mark: |
4.1.3...4.5.1 | ~4.0.4 (ref) | Yes :heavy_check_mark: |
3.0.5...4.1.2 | ~4.0.3 (ref) | Yes :heavy_check_mark: |
3.0.0...3.0.4 | ~4.0.1 (ref) | Yes :heavy_check_mark: |
2.3.0...2.5.0 | ~3.4.0 (ref) | Yes :heavy_check_mark: |
Dependency analysis for the socket.io-client package
socket.io-client version | socket.io-parser version | Covered? |
|---|---|---|
4.5.0...latest | ~4.2.0 (ref) | Yes :heavy_check_mark: |
4.3.0...4.4.1 | ~4.1.1 (ref) | No, but the impact is very limited |
3.1.0...4.2.0 | ~4.0.4 (ref) | Yes :heavy_check_mark: |
3.0.5 | ~4.0.3 (ref) | Yes :heavy_check_mark: |
3.0.0...3.0.4 | ~4.0.1 (ref) | Yes :heavy_check_mark: |
2.2.0...2.5.0 | ~3.3.0 (ref) | Yes :heavy_check_mark: |
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | socket.io-parser | ≥ 4.0.0&&< 4.0.5 | 4.0.5npm install socket.io-parser@4.0.5 |
| 📦npm | socket.io-parser | ≥ 4.1.0&&< 4.2.1 | 4.2.1npm install socket.io-parser@4.2.1 |
| 📦npm | socket.io-parser | all versions | 3.3.3npm install socket.io-parser@3.3.3 |
| 📦npm | socket.io-parser | ≥ 3.4.0&&< 3.4.2 | 3.4.2npm install socket.io-parser@3.4.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for socket.io-parser, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update socket.io-parser to 4.0.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-qm95-pgcg-qqfq 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 GHSA-qm95-pgcg-qqfq can be triaged on real exposure rather than presence alone.
Tailored to GHSA-qm95-pgcg-qqfq. 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-qm95-pgcg-qqfq in your dependencies?
O3 Security finds GHSA-qm95-pgcg-qqfq across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.