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CVE-2026-59876

protobufjs: Text Format string map parsing can mutate returned map object prototype

Published: Jul 8, 2026Updated: Jul 13, 2026 Sources: CVE List NVDCWE-1321
4.8MEDIUM
NVD MITRE
EPSS Score
0.3%
Top 72.1%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available
Self-Check
Not available

Description

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.

No summary for this CVE yet.

CVSS Vector Breakdown

AV:NAC:HPR:NUI:NS:UC:LI:LA:N
Exploitability
AV:NAttack Vector
Network
AC:HAttack Complexity
High
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:LConfidentiality
Low
I:LIntegrity
Low
A:NAvailability
None
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Weaknesses

CWE-1321

Affected Products

protobufjs
oss-projectaka protobuf.js
protobuf.jsLibrary
OSS Libraries / generic-library
protobufjs project
oss-projectaka protobufjs, protobufjs-cli
protobufjsLibrary
OSS Libraries / generic-library

Exploitability

Official Patch Available
Workaround Available

Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

1 technique
Execution
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References

https://github.com/protobufjs/protobuf.js/security/advisories/GHSA-jfj6-75fj-8934
github.com
https://github.com/protobufjs/protobuf.js/pull/2335
github.com
https://github.com/protobufjs/protobuf.js/commit/9f97fe413072d3beb52c74e62d88ea8adc9444d8
github.com
and 1 more references View all →

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