GHSA-66ff-xgx4-vchm
GHSA-66ff-xgx4-vchm is a security vulnerability in protobufjs. O3 Security confirms whether GHSA-66ff-xgx4-vchm is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
protobuf.js: Code injection through bytes field defaults in generated toObject code
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, a proxy for how much of the ecosystem is exposed.
protobufjsnpmDescription
Summary
protobufjs generated JavaScript for toObject conversion could include an unsafe expression derived from a schema-controlled bytes field default value. A crafted descriptor with a non-string default value for a bytes field could cause attacker-controlled code to be emitted into the generated conversion function.
Impact
An attacker who can provide or influence a protobuf descriptor may be able to execute arbitrary JavaScript in the context of the process using protobufjs.
This requires the application to load an attacker-controlled schema or descriptor and then convert a message of the affected type with defaults enabled. Applications that only use trusted, application-defined schemas are not directly affected by this issue.
Preconditions
- The application must allow an attacker to control or influence a protobuf JSON descriptor or equivalent reflected schema.
- The descriptor must define a
bytesfield with an attacker-controlled default value. - The application must call
toObjectwith defaults enabled for the affected type.
Workarounds
Do not load protobuf schemas or JSON descriptors from untrusted sources with affected versions. If untrusted schemas must be accepted, validate or restrict field options before loading them and run schema processing in an isolated environment.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | protobufjs | all versions | 7.5.6 |
| 📦npm | protobufjs | ≥ 8.0.0&&< 8.0.2 | 8.0.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for protobufjs. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update protobufjs to 7.5.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-66ff-xgx4-vchm 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 pinpoints whether GHSA-66ff-xgx4-vchm is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-66ff-xgx4-vchm. 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-66ff-xgx4-vchm in your dependencies?
O3 detects GHSA-66ff-xgx4-vchm across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.