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Researchers disclosed six vulnerabilities, dubbed Proto6, in the widely used protobuf.js ecosystem that can enable remote code execution, denial of service, prototype pollution, and prototype injection in affected Node.js environments. The most severe flaw, CVE-2026-44291, allows arbitrary JavaScript execution through prototype pollution combined with unsafe code-generation behavior, while other issues involve recursion-based crashes, unsafe schema option path handling, crafted field-name abuse, and code injection in pbjs static output.
The bugs affect applications and build pipelines that deserialize Protocol Buffers data or generate code from schemas using protobuf.js, including Google Cloud client libraries, gRPC-related tooling, messaging frameworks such as Baileys, and CI/CD workflows. Researchers said the library is deeply embedded across the JavaScript ecosystem, with more than 50 million weekly downloads and frequent transitive inclusion that can make exposure hard to identify. Fixed versions are available in protobufjs 7.5.6 and 8.0.2, and in protobufjs-cli 1.2.1 and 2.0.2; vulnerable releases include protobuf.js through 7.5.5 and 8.0.0-8.0.1, and protobufjs-cli through 1.2.0 and 2.0.0-2.0.1.
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Fixes were made available for the affected packages, including protobuf.js versions 7.5.6 and 8.0.2 and protobufjs-cli versions 1.2.1 and 2.0.2. The patched releases address the six disclosed Proto6 vulnerabilities.
Cyera researchers disclosed six vulnerabilities, collectively named Proto6, affecting protobuf.js and protobufjs-cli. The issues can enable remote code execution, denial of service, prototype pollution, prototype injection, and code-generation abuse in affected Node.js environments.
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A vulnerability in the npm package **`protobufjs`** allows arbitrary JavaScript execution when an application processes attacker-controlled protobuf definition files. The flaw, tracked as **`GHSA-xq3m-2v4x-88gg`**, stems from unsafe handling of protobuf **`type`** fields, which can be compiled into executable JavaScript and triggered during object decoding, creating a path to remote code execution in affected deployments. The issue affects **`protobufjs`** versions up to **`8.0.0`** and **`7.5.4`**, and has been fixed in **`8.0.1`** and **`7.5.5`**. A published proof of concept shows a malicious JSON descriptor invoking Node.js **`child_process`** during decode, underscoring the risk for applications that ingest untrusted schema or descriptor data. Organizations using `protobufjs` should upgrade to the patched releases and review whether external parties can supply protobuf definitions.
Jun 29, 2026
Two high-severity flaws were disclosed in widely used JavaScript libraries, exposing applications to sandbox bypass and arbitrary code execution. **CVE-2026-34208** affects SandboxJS before `0.8.36` and allows attacker-supplied code to evade protections on direct assignment to global objects by abusing an exposed constructor path. The bypass uses `this.constructor.call(target, attackerObject)` to reach the internal `SandboxGlobal` function while `Function.prototype.call` remains permitted, enabling arbitrary properties to be written into host global objects and persist across sandbox instances in the same process. A separate issue, **CVE-2026-41242**, impacts `protobufjs` before `8.0.1` and `7.5.5`, where attackers can inject arbitrary code into Protocol Buffers definition `type` fields and trigger execution during object decoding with a malicious schema. The flaw is tracked as **CWE-94** and carries a CVSS v4 rating reflecting network-reachable exploitation with high impact to confidentiality, integrity, availability, and downstream systems. Maintainers released fixes in SandboxJS `0.8.36` and protobufjs `8.0.1` and `7.5.5`.
Jun 29, 2026
Two critical prototype pollution vulnerabilities, **CVE-2026-48713** and **CVE-2026-48714**, were disclosed in the widely used Node.js internationalization components **`i18next-fs-backend`** and **`i18next-http-middleware`**. The bugs allow attacker-controlled missing translation keys to traverse unsafe path segments such as `__proto__`, `constructor`, and `prototype`, potentially writing arbitrary properties into **`Object.prototype`**. In affected deployments, successful exploitation can trigger application crashes, corrupt translation behavior, poison configuration, and bypass property-based security checks. The primary backend flaw affects **`i18next-fs-backend`** versions before **`2.6.6`**, while the middleware flaw affects **`i18next-http-middleware`** versions before **`3.9.7`** and can help remote input reach the vulnerable backend path by failing to block dotted payloads such as `__proto__.polluted`. Exploitation depends on applications exposing **`missingKeyHandler`** or similar **`saveMissing`** functionality to untrusted users with key splitting enabled. Maintainers patched the issues by blocking unsafe path traversal, and defenders are advised to upgrade immediately, restrict missing-key routes to trusted users, disable missing-key persistence for untrusted input, or set **`keySeparator`** to **`false`** where appropriate.
Jun 29, 2026