Security firm Endor Labs disclosed a critical remote code execution flaw in protobuf.js, a widely used JavaScript implementation of Google's Protocol Buffers with nearly 50 million weekly downloads on npm. The bug lets attackers achieve RCE when an application loads a malicious protobuf schema. Root cause: protobuf.js builds JavaScript functions from protobuf schemas by concatenating strings and executing them via the Function() constructor, but doesn't validate schema-derived identifiers like message names. An attacker can supply a crafted schema that injects arbitrary JavaScript into the generated function, which then runs when the app processes any message using that schema. This opens access to environment variables, credentials, databases, and internal systems - plus lateral movement within infrastructure. Developer machines are also at risk if they load and decode untrusted schemas locally. The flaw has a proof-of-concept exploit in Endor Labs' advisory and 'exploitation is straightforward' per the researchers, but no in-the-wild exploitation has been observed yet. No official CVE assigned - tracked as GHSA-xq3m-2v4x-88gg. Reported March 2 by Cristian Staicu, patched on GitHub March 11, npm patches released April 4 (8.x branch) and April 15 (7.x branch).
TrustStrike Labs