Browserslist up to 4.28.6 Stats Normalization normalizeStats prototype pollution

Summaryinfo

A vulnerability was found in Browserslist up to 4.28.6 and classified as critical. This issue affects the function normalizeStats of the component Stats Normalization. The manipulation results in prototype pollution. This vulnerability is cataloged as CVE-2026-73088. The attack may be launched remotely. There is no exploit available.

Detailsinfo

A vulnerability classified as critical has been found in Browserslist up to 4.28.6. Affected is the function normalizeStats of the component Stats Normalization. The manipulation with an unknown input leads to a prototype pollution vulnerability. CWE is classifying the issue as CWE-1321. The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

Browserslist is a configuration tool for sharing target browsers and Node.js versions between front-end tools. Prior to 4.28.7, normalizeStats() in node.js, reached unconditionally through getStat() and loadStat() on every browserslist() call, processes untrusted browserslist-stats.json, opts.stats, and CLI --stats data with an unguarded for...in loop and plain-object bracket access and assignment, allowing inherited Object.prototype keys including __proto__, toString, valueOf, constructor, hasOwnProperty, and isPrototypeOf to cause an uncaught TypeError or modify the prototype of the returned normalized object. This issue is fixed in version 4.28.7.

The advisory is available at github.com. This vulnerability is traded as CVE-2026-73088 since 08/10/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1059 by the MITRE ATT&CK project.

Upgrading to version 4.28.7 eliminates this vulnerability.

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Productinfo

Name

• Browserslist

Version

• 4.28.0
• 4.28.1
• 4.28.2
• 4.28.3
• 4.28.4
• 4.28.5
• 4.28.6

Website

• Product: https://github.com/browserslist/browserslist/

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