CVE-2026-91766

Cross-origin credential leak in HTTP stream wrapper redirects

MEDIUM
5.9
CVSS Score
Published: September 25, 2026 at 08:40 PM UTC
Updated: October 23, 2026 at 01:46 PM UTC
1 product affected across 1 vendorPHP

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Severity
MEDIUM5.9
Exploit prediction
EPSS 0.3%
SSVC
No known exploit

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 ).

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

PHP· PHPdrupal
95%
8.2.0 ≤ v < 8.2.348.3.0 ≤ v < 8.3.358.4.0 ≤ v < 8.4.268.5.0 ≤ v < 8.5.118.2.*8.3.*8.4.*8.5.*
Affected range stops below 8.2.34, so it looks safe — our inference, not a vendor statement
Affected range stops below 8.3.35, so it looks safe — our inference, not a vendor statement
Affected range stops below 8.4.26, so it looks safe — our inference, not a vendor statement
Affected range stops below 8.5.11, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (1)

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

5.9MEDIUMphp
Attack Vector
NETWORK
Complexity
HIGH
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-200CWE-522

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