VDB-376942 · CVE-2026-59876 · GCVE-0-2026-59876

protobuf.js up to 8.6.4 Text Format Extension /ext/textformat proto insufficient precision or accuracy of a real number

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
7.0	$0-$5k	0.58+

Summaryinfo

A vulnerability was found in protobuf.js up to 8.6.4. It has been declared as critical. Impacted is an unknown function of the file /ext/textformat of the component Text Format Extension. Executing a manipulation of the argument __proto__ can lead to insufficient precision or accuracy of a real number. This vulnerability is tracked as CVE-2026-59876. The attack can be launched remotely. No exploit exists.

Detailsinfo

A vulnerability has been found in protobuf.js up to 8.6.4 and classified as critical. This vulnerability affects some unknown processing of the file /ext/textformat of the component Text Format Extension. The manipulation of the argument __proto__ with an unknown input leads to a insufficient precision or accuracy of a real number vulnerability. The CWE definition for the vulnerability is CWE-1339. The product processes a real number with an implementation in which the number's representation does not preserve required accuracy and precision in its fractional part, causing an incorrect result. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is available at github.com. This vulnerability was named CVE-2026-59876 since 07/07/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Technical details are known, but there is no available exploit.

Upgrading to version 8.6.5 eliminates this vulnerability.

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Productinfo

Type

JavaScript Library

Name

protobuf.js

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.3
VulDB Meta Temp Score: 7.0

VulDB Base Score: 7.3
VulDB Temp Score: 7.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Insufficient precision or accuracy of a real number
CWE: CWE-1339
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔒

Upgrade: protobuf.js 8.6.5

Timelineinfo

07/07/2026 CVE reserved
07/08/2026 +1 days Advisory disclosed
07/08/2026 +0 days VulDB entry created
07/08/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: github.com
Status: Confirmed

CVE: CVE-2026-59876 (🔒)
GCVE (CVE): GCVE-0-2026-59876
GCVE (VulDB): GCVE-100-376942

Entryinfo

Created: 07/08/2026 19:08
Changes: 07/08/2026 19:08 (55)
Complete: 🔍
Cache ID: 216::103