Information disclosure in PHP
CVE-2026-91766
When the http:// stream wrapper follows a redirect it forwards the user-supplied Authorization, Cookie and Proxy-Authorization headers unchanged, even when the redirect target is a different host, a different port, or a downgrade from HTTPS to HTTP. A server that can steer a redirect therefore receives credentials that were only meant for the original origin. This is the same class of issue that libcurl fixed in 7.58.0 ( CVE-2018-1000007 https://github.com/advisories/GHSA-g7x2-hrfp-pv5f ).
Vulnerability class: Information Disclosure
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N.
EPSS exploit prediction
EPSS: 0.003 (21.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 21st percentile — 21.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: -0.001
Affected products
Weakness classification (CWE)
References
- github.com/php/php-src/security/advisories/GHSA-fpwc-w8rq-cr92 (Exploit, vendor-advisory, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-91766?
- CVE-2026-91766 is a medium-severity vulnerability in PHP, classified under Information Disclosure. CVSS score: 5.9/10. Published 2026-09-25.
- How severe is CVE-2026-91766?
- Medium severity. CVSS v3 base score is 5.9 out of 10.