Prototype Pollution in Browserslist

CVE-2026-73088

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.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.007 (49.5th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 49th percentile — 49.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-73088: held from 0.004 to 0.007.

EPSS over last 30 days · oldest: 0.004 · newest: 0.007 · change: +0.003

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-73088?
CVE-2026-73088 is a high-severity vulnerability in Browserslist, classified under CWE-248. CVSS score: 7.5/10. Published 2026-08-11.
How severe is CVE-2026-73088?
High severity. CVSS v3 base score is 7.5 out of 10.