protobuf.js: Prototype injection in generated message constructorsGHSA-fx83-v9x8-x52w
MEDIUMGHSA-fx83-v9x8-x52w is a medium-severity (CVSS 5.3) CWE-1321 vulnerability in protobufjs. A fix is available for protobufjs — see the affected versions and patch details below.
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.
- 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-fx83-v9x8-x52w.
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.
protobufjsnpmDescription
Summary
protobufjs generated message constructors copied enumerable properties from a provided properties object without filtering the __proto__ key. If an application constructed a message from an attacker-controlled plain object, an own enumerable __proto__ property could alter the prototype of that individual message instance.
Impact
An attacker who can control the properties object passed to a generated protobufjs message constructor or creation helper may be able to modify the prototype chain of the resulting message instance.
This is a per-instance prototype injection issue. It does not pollute Object.prototype or other global prototypes. The impact depends on downstream application behavior, such as relying on inherited properties, prototype methods, or instanceof checks for message objects.
Applications that only decode binary protobuf data, or that construct messages from trusted application-defined objects, are not directly affected by this issue.
Preconditions
- The application must allow an attacker to control or influence a plain object used to construct a protobufjs message.
- The object must contain an own enumerable
__proto__property, for example from parsed JSON input. - The application must pass that object to a generated message constructor or creation helper that copies arbitrary enumerable properties.
Workarounds
Do not pass attacker-controlled plain objects directly to generated message constructors with affected versions. If untrusted JSON input must be accepted, validate or sanitize object keys before constructing messages, and reject __proto__ properties.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | protobufjs | all versions | 7.5.6npm install protobufjs@7.5.6 |
| 📦npm | protobufjs | ≥ 8.0.0&&< 8.0.2 | 8.0.2npm install protobufjs@8.0.2 |
Affected Products
protobufjsprotobufjs_projectDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for protobufjs, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update protobufjs to 7.5.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-fx83-v9x8-x52w 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.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
This is an Important vulnerability where `protobufjs` can be exploited for prototype pollution on individual message instances. Applications that construct `protobufjs` messages from attacker-controlled plain objects, particularly those parsing untrusted JSON input, are susceptible to data integrity issues through…
To mitigate this issue, applications should avoid directly passing attacker-controlled plain objects to protobufjs message constructors. If processing untrusted JSON input, it is crucial to validate or sanitize object keys and explicitly reject any `__proto__` properties before constructing protobuf messages. This operational control prevents the manipulation of message instance prototypes.Source: Red Hat security advisory for GHSA-fx83-v9x8-x52w (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| Cryostat 4 on RHEL 9 | cryostat/cryostat-grafana-dashboard-rhel9:4.2.0-13 | RHSA-2026:48151 |
| Red Hat Ansible Automation Platform 2.2 | ansible-automation-platform/automation-portal:1784622951 | RHSA-2026:42815 |
| Red Hat OpenShift AI 3.4 | rhoai/odh-dashboard-rhel9:1787347991 | RHSA-2026:60520 |
| Red Hat OpenShift AI 3.4 | rhoai/odh-mod-arch-eval-hub-rhel9:1791861214 | RHSA-2026:84734 |
| Red Hat OpenShift Container Platform 4.18 | openshift4/ose-console-rhel9:1787031447 | RHSA-2026:57487 |
Frequently Asked Questions
Is GHSA-fx83-v9x8-x52w in your dependencies?
Find it across npm, including transitive dependencies.