CVE-2026-104459
Deferred Deferred - Pending Action

Server-Side Request Forgery in YesWiki Prior to 4.6.7

Publication date: 2026-10-02

Last updated on: 2026-10-02

Assigner: VulnCheck

Description
YesWiki before 4.6.7 contains a server-side request forgery vulnerability in WebfingerService that allows unauthenticated attackers to trigger HTTPS requests to internal hosts. Attackers can POST a crafted actor_handle with a numeric host and port to the abonnements view to probe internal HTTPS services and ports.

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Meta Information

Published
2026-10-02
Last Modified
2026-10-02
Generated
2026-10-02
AI Q&A
2026-10-02
EPSS Evaluated
N/A
NVD
CVE-2026-104459
EUVD
EUVD-2026-91470

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
yeswiki yeswiki to 4.6.7 (exc)

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-918 The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.

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Executive Summary

CVE-2026-104459 is a Server-Side Request Forgery (SSRF) vulnerability in YesWiki versions before 4.6.7. It exists in the WebfingerService component where attackers can manipulate the actor_handle parameter to craft a malicious URL. This URL is fetched server-side without proper host or IP validation, allowing attackers to probe internal HTTPS services or perform port scanning on the server's network.

Detection Guidance

To detect this SSRF vulnerability, monitor for unusual HTTPS requests originating from your YesWiki server to internal hosts or ports. Check web server logs for POST requests to the abonnements view with actor_handle parameters containing numeric hosts or ports. Use network monitoring tools like tcpdump or Wireshark to capture outbound HTTPS traffic from the server.

Impact Analysis

An attacker can exploit this to probe internal HTTPS services and ports on your network, potentially accessing restricted internal resources. The attack can be triggered via a POST request to the abonnements view with a crafted actor_handle parameter, even without authentication.

Compliance Impact

This SSRF vulnerability could potentially impact compliance with GDPR and HIPAA by enabling unauthorized access to internal HTTPS services. Attackers can probe internal systems, which may expose sensitive data or internal network information, violating data protection requirements for confidentiality and integrity.

Mitigation Strategies

Immediately upgrade YesWiki to version 4.6.7 or later. If upgrading is not possible, implement input validation to reject numeric, loopback, private, or link-local hosts in the actor_handle parameter. Add ACL checks to the abonnements view to prevent unauthorized POST requests. Block outbound HTTPS requests to internal IP ranges at the firewall level.

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