Prototype Pollution in Crcn Sift.js
CVE-2026-85625
sift (sift.js) 17.1.3 enumerates query keys with for...in, which walks the object prototype chain, and dispatches any matched operator key including $where. The $where operation compiles a string value into a function using new Function unless CSP_ENABLED is set (not set by default). As a result, if a prototype-pollution primitive elsewhere in the process sets Object.prototype.$where to a malicious string, even benign filter calls such as sift({}) execute arbitrary JavaScript. Additionally, passing an untrusted query object containing a string $where directly to sift results in code execution under the default configuration.
Vulnerability class: Prototype Pollution
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.007 (53.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 54th percentile — 53.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.007 · change: +0.002
Affected products
Weakness classification (CWE)
Public proof-of-concept exploits
References
- github.com/crcn/sift.js (product)
- github.com/crcn/sift.js/blob/v17.1.3/src/core.ts (technical-description)
- github.com/crcn/sift.js/issues/276 (issue-tracking)
- www.vulncheck.com/advisories/sift-17.1.3-prototype-pollution-remote-code-execut… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-85625?
- CVE-2026-85625 is a high-severity vulnerability in Crcn Sift.js, classified under Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution). CVSS score: 8.1/10. Published 2026-09-04.
- How severe is CVE-2026-85625?
- High severity. CVSS v3 base score is 8.1 out of 10.
- Is CVE-2026-85625 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.