CVE-2026-59876
MEDIUMprotobufjs: Text Format string map parsing can mutate returned map object prototype
Title source: cnaDescription
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.
References (4)
Core 4
Core References
X_Refsource_Confirm x_refsource_confirm
https://github.com/protobufjs/protobuf.js/security/advisories/GHSA-jfj6-75fj-8934
X_Refsource_Misc x_refsource_misc
https://github.com/protobufjs/protobuf.js/pull/2335
X_Refsource_Misc x_refsource_misc
https://github.com/protobufjs/protobuf.js/commit/9f97fe413072d3beb52c74e62d88ea8adc9444d8
X_Refsource_Misc x_refsource_misc
https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v8.6.5
Scores
CVSS v3
4.8
EPSS
0.0022
EPSS Percentile
12.4%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
CISA SSVC
Vulnrichment
Exploitation
none
Automatable
no
Technical Impact
partial
Details
CWE
CWE-1321
Status
published
Products (2)
protobufjs/protobuf.js
>= 8.2.0, < 8.6.5
protobufjs_project/protobufjs
8.2.0 - 8.6.5
Published
Jul 08, 2026
Tracked Since
Jul 08, 2026