CVE-2026-40895: follow-redirects: Custom Authentication Headers Leaked to Cross-Domain Redirect Targets

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-04-21 · updated 2026-09-10
Weakness: CWE-200

Description

follow-redirects is an open source, drop-in replacement for Node's `http` and `https` modules that automatically follows redirects. Prior to 1.16.0, when an HTTP request follows a cross-domain redirect (301/302/307/308), follow-redirects only strips authorization, proxy-authorization, and cookie headers (matched by regex at index.js). Any custom authentication header (e.g., X-API-Key, X-Auth-Token, Api-Key, Token) is forwarded verbatim to the redirect target. This vulnerability is fixed in 1.16.0.

Affected products

follow-redirects: before 1.16.0 — fixed in 1.16.0
Npm Follow-Redirects: before 1.16.0 — fixed in 1.16.0

How to fix

Upgrade to a fixed version: follow-redirects 1.16.0; Npm Follow-Redirects 1.16.0. Check the vendor advisory for mitigations.

References

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