CVE-2026-91766
Cross-origin credential leak in HTTP stream wrapper redirects
Description
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 ).
INFO
Published Date :
Sept. 25, 2026, 9:17 p.m.
Last Modified :
Sept. 25, 2026, 9:17 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | MEDIUM | dd77f84a-d19a-4638-8c3d-a322d820ed2b | ||||
| CVSS 3.1 | MEDIUM | [email protected] |
Solution
- Update http stream wrapper implementation.
- Prevent header forwarding on cross-origin redirects.
- Strip sensitive headers on HTTPS to HTTP downgrades.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-91766.
| URL | Resource |
|---|---|
| https://github.com/php/php-src/security/advisories/GHSA-fpwc-w8rq-cr92 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-91766 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-91766
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-91766 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-91766 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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New CVE Received by [email protected]
Sep. 25, 2026
Action Type Old Value New Value Added Description 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 ). Added CVSS V3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N Added CWE CWE-200 Added CWE CWE-522 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/91xxx/CVE-2026-91766.json">CVE-2026-91766</a> Added Reference https://github.com/php/php-src/security/advisories/GHSA-fpwc-w8rq-cr92