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.
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.
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.
Untrusted input is evaluated as executable code within the application's runtime environment. Typical impact: arbitrary code execution within the application's privilege context.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
protobufjs to 7.5.6 or later; protobufjs to 8.0.2 or later
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2026-44293? CVE-2026-44293 is a high-severity code injection vulnerability in protobufjs (npm), affecting versions <= 7.5.5. It is fixed in 7.5.6, 8.0.2. Untrusted input is evaluated as executable code within the application's runtime environment.
- Which versions of protobufjs are affected by CVE-2026-44293? protobufjs (npm) versions <= 7.5.5 is affected.
- Is there a fix for CVE-2026-44293? Yes. CVE-2026-44293 is fixed in 7.5.6, 8.0.2. Upgrade to this version or later.
- Is CVE-2026-44293 exploitable, and should I be worried? Whether CVE-2026-44293 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-44293 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-44293?
- Upgrade
protobufjsto 7.5.6 or later - Upgrade
protobufjsto 8.0.2 or later
- Upgrade