CVE-2026-47099

Description

TeleJSON prior to 6.0.0 contains a DOM-based cross-site scripting vulnerability in the parse() function that allows attackers to execute arbitrary JavaScript by delivering a crafted JSON payload containing a malicious _constructor-name_ property value. The custom reviver passes the constructor name directly to new Function() without sanitization when recreating object prototypes, enabling attackers to inject arbitrary JavaScript through vectors such as postMessage in cross-frame communication contexts to achieve script execution within the application.

CVSS v3.1 Score

6.1

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS — Exploit Prediction

0.0003

Probability of exploitation

0.10%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-79 Cross-site Scripting (XSS)

References

Other References

https://github.com/Niccolo10/Security-Advisories/blob/main/CVE-2026-47099/cve-2026-47099.md https://github.com/storybookjs/telejson/security/advisories/GHSA-ccgf-5rwj-j3hv https://www.vulncheck.com/advisories/telejson-dom-based-xss-via-parse-function

Frequently Asked Questions

What is CVE-2026-47099? +

TeleJSON prior to 6.0.0 contains a DOM-based cross-site scripting vulnerability in the parse() function that allows attackers to execute arbitrary JavaScript by delivering a crafted JSON payload containing a malicious _constructor-name_ property value. The custom reviver passes the constructor name directly to new Function() without sanitization when recreating object prototypes, enabling attackers to inject arbitrary JavaScript through vectors such as postMessage in cross-frame communication contexts to achieve script execution within the application. It has a CVSS v3.1 base score of 6.1 (MEDIUM).

How severe is CVE-2026-47099? +

CVE-2026-47099 has a CVSS v3.1 score of 6.1 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0003, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-47099? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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