Cross-origin credential leak in HTTP stream wrapper redirects (CVE-2026-91766)

What is affected, what to do

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.

An exploit is publicly available. Update PHP to version 8.2.34, PHP to version 8.3.35, PHP to version 8.4.26.

Affected

• PHP lt 8.2.0..8.2.34
• PHP lt 8.3.0..8.3.35
• PHP lt 8.4.0..8.4.26
• PHP lt 8.5.0..8.5.11

Fixed in

• PHP 8.2.34
• PHP 8.3.35
• PHP 8.4.26
• PHP 8.5.11

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Metrics

Detection rules

No NEOSEC detection rule is available for this vulnerability yet.

Classification under NIS2 and CRA

Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

NIS2

NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

Read in glossary

Handle the vulnerability in regular vulnerability handling under Art. 21(2)(e) NIS2.

CRA

The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

Read in glossary

From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.

ISO/IEC 27001

ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

Read in glossary

Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

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 ).

Source: suse_csaf, redhat_csaf, Ubuntu Security Notices, Debian Security Advisories, Debian LTS Advisories, BSI WID Portal, BSI CSAF, OSV (Open Source Vulnerabilities), Microsoft Security Update Guide, cvelistv5, NVD (NIST), CVE.org (MITRE)

Vendors and products

• Debian Php8.2
• Debian Php8.4
• Open Source PHP
• PHP Group PHP
• PHP Group PHP
• Ubuntu Php5
• Ubuntu Php7.0
• Ubuntu Php7.2
• Ubuntu Php7.4
• Ubuntu Php8.1
• Ubuntu Php8.3
• Ubuntu Php8.5

Weakness classes (CWE)

• CWE-200Exposure of Sensitive Information to an Unauthorized Actor

  Class

  The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.

  Entry at MITRE CWE-200

• CWE-522Insufficiently Protected Credentials

  Class

  The product transmits or stores authentication credentials, but it uses an insecure method that is susceptible to unauthorized interception and/or retrieval.

  Entry at MITRE CWE-522

References & sources

• github.comphp/php-src/security/advisories/GHSA-fpwc-w8rq-cr92Vendor advisory, Vendor advisory, Exploit, advisory
• NVD (NIST)vuln/detail/CVE-2026-91766web

Changes to this CVE

Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

1. 23.10.2026Initial analysis by NVDNVD

   Newly listed as affected:

   • PHP (8.2.0 – before 8.2.34; 8.3.0 – before 8.3.35; 8.4.0 – before 8.4.26; 8.5.0 – before 8.5.11)

   CVSS V3.1: AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

   New references:

   • https://github.com/php/php-src/security/advisories/GHSA-fpwc-w8rq-cr92
   Show 3 original changes

   Individual changes of this event as published by NVD

   Type	Action	Before	After
   CVSS	added	—	AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
   Product configuration	added	—	OR *cpe:2.3:a:php:php:*:*:*:*:*:*:*:* versions from (including) 8.2.0 up to (excluding) 8.2.34 *cpe:2.3:a:php:php:*:*:*:*:*:*:*:* versions from (including) 8.3.0 up to (excluding) 8.3.35 *cpe:2.3:a:php:php:*:*:*:*:*:*:*:* versions from (including) 8.4.0 up to (excluding) 8.4.26 *cpe:2.3:a:php:php:*:*:*:*:*:*:*:* versions from (including) 8.5.0 up to (excluding) 8.5.11
   Reference type	added	—	PHP Group: https://github.com/php/php-src/security/advisories/GHSA-fpwc-w8rq-cr92 Types: Exploit, Vendor Advisory

   Source identifier: nvd@nist.gov

2. 28.09.2026Record modifiedCISA ADP

   CISA assessment (SSVC): exploitation: none known, automatable: no

   Show the original change

   Individual changes of this event as published by NVD

   Type	Action	Before	After
   SSVC assessment	added	—	{"id":"CVE-2026-91766","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"partial"}],"version":"2.0.3","timestamp":"2026-09-28T12:56:20.823835Z"}

   Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0

3. 25.09.2026ReceivedPHP

   CVSS V3.1: AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

   Weakness type: CWE-200, CWE-522

   Description added or changed

   New references:

   • https://github.com/php/php-src/security/advisories/GHSA-fpwc-w8rq-cr92
   Show 6 original changes

   Individual changes of this event as published by NVD

   Type	Action	Before	After
   Description	added	—	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 ).
   CVSS	added	—	AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
   Weakness type (CWE)	added	—	CWE-200
   Weakness type (CWE)	added	—	CWE-522
   Affected versions (publisher)	added	—	New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/91xxx/CVE-2026-91766.json">CVE-2026-91766</a>
   Reference	added	—	https://github.com/php/php-src/security/advisories/GHSA-fpwc-w8rq-cr92

   Source identifier: security@php.net