Insufficiently protected credentials in PHP - CVE-2026-91766
Published: September 24, 2026
Vulnerability identifier: #VU151925
CSH Severity: Medium
CVSS v4: 8.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-91766
CWE-ID: CWE-522
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to disclose credentials.
The vulnerability exists due to improper credential forwarding in the HTTP stream wrapper when following a cross-origin redirect. A remote attacker can control a redirect target to disclose credentials.
The issue affects user-supplied Authorization, Cookie, and Proxy-Authorization headers, including redirects from HTTPS to HTTP.
Affected software
PHP
How to mitigate CVE-2026-91766
Install security update from vendor's website.
PHP - addressed in versions 8.2.34, 8.3.35, 8.4.26, 8.5.11