What’s Vulnerable › Vulnerabilities

CVE-2021-23387: Open Redirect

• Severity: medium (CVSS 6.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.1% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2021-05-24 · updated 2026-06-17
• Weakness: CWE-601

Description

The package trailing-slash before 2.0.1 are vulnerable to Open Redirect via the use of trailing double slashes in the URL when accessing the vulnerable endpoint (such as https://example.com//attacker.example/). The vulnerable code is in index.js::createTrailing(), as the web server uses relative URLs instead of absolute URLs.

Affected products

• trailing-slash: before 2.0.1 — fixed in 2.0.1

How to fix

Upgrade to a fixed version: trailing-slash 2.0.1. Check the vendor advisory for mitigations.

References

• https://github.com/fardog/trailing-slash/blob/f640ece055fe85275c983de5eb94661b95e35670/index.js%23L36
• https://github.com/fardog/trailing-slash/commit/f8e66f1429308247e5a119d430203077d8f05048
• https://snyk.io/vuln/SNYK-JS-TRAILINGSLASH-1085707
• https://github.com/fardog/trailing-slash/blob/f640ece055fe85275c983de5eb94661b95e35670/index.js%23L36
• https://github.com/fardog/trailing-slash/commit/f8e66f1429308247e5a119d430203077d8f05048
• https://snyk.io/vuln/SNYK-JS-TRAILINGSLASH-1085707

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