CVE-2026-59876 — protobufjs: Text Format string map parsing can mutate returned map object prototype
protobufjs compiles protobuf definitions into JavaScript (JS) functions. From 8.2.0 until 8.6.5, the protobufjs Text Format extension parsed string-keyed map entries using ordin…
Published: 2026-07-08 · CVSS: 4.8 · CVSS 3.1
protobufjs compiles protobuf definitions into JavaScript (JS) functions. From 8.2.0 until 8.6.5, the protobufjs Text Format extension parsed string-keyed map entries using ordinary property assignment, allowing a map entry with key __proto__ to change the prototype of the returned map object instead of creating an own map entry in protobufjs/ext/textformat. This issue is fixed in version 8.6.5.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7