CVE-2026-54271 — protobufjs-cli
HIGHCVE-2026-54271 is a high-severity (CVSS 8.2) Code Injection vulnerability in protobufjs-cli. A fix is available for protobufjs-cli — see the affected versions and patch details below.
protobufjs-cli: Code injection in pbjs static output from crafted JSON descriptor names
Exploitation Status
No confirmed exploitation observed yet
- 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 CVE-2026-54271.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-54271 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 379,842 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
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.
protobufjs-clinpmDescription
Summary
A previous fix for unsafe name handling in pbjs static / static-module code generation was incomplete. Affected versions of protobufjs-cli could still emit unsafe JavaScript references when generating static output from crafted JSON descriptor input. The common case of parsing schemas from .proto files is not affected.
This is a bypass of GHSA-6r35-46g8-jcw9 / CVE-2026-44295.
Impact
An attacker who can provide or influence pre-parsed JSON descriptors passed to pbjs static code generation may be able to cause generated JavaScript output to contain attacker-controlled code.
The injected code may execute if the generated file is later executed or imported and an affected generated API path is invoked.
Preconditions
- The application or build process must run
pbjsstatic code generation on a pre-parsed JSON descriptor influenced by an attacker. - The generated JavaScript file must subsequently be executed or imported.
- An affected generated API path must be invoked.
Workarounds
Do not run affected versions of pbjs static or static-module generation on untrusted JSON descriptors. If untrusted JSON descriptors must be accepted, validate descriptor-derived names before code generation and reject names that could not have been produced by parsing a valid .proto file. Running code generation in an isolated environment can reduce impact.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | protobufjs-cli | all versions | 1.3.2npm install protobufjs-cli@1.3.2 |
| 📦npm | protobufjs-cli | ≥ 2.0.0&&< 2.5.0 | 2.5.0npm install protobufjs-cli@2.5.0 |
Affected Products
protobufjs-cliprotobufjs_projectDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for protobufjs-cli, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update protobufjs-cli to 1.3.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-54271 is resolved across your whole dependency graph.
Workarounds
Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.
Frequently Asked Questions
Is CVE-2026-54271 in your dependencies?
Find it across npm, including transitive dependencies.