CVE-2026-104458
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 validateKeyIdUrl() that allows unauthenticated attackers to bypass the SSRF guard using 6to4, NAT64, or IPv4-compatible IPv6 addresses. Attackers can send a crafted Signature keyId to the public actor inbox route to reach cloud metadata, loopback services, or internal hosts.

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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-2026-104458
EUVD
EUVD-2026-91469

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-2026-104458 is a server-side request forgery (SSRF) vulnerability in YesWiki versions before 4.6.7. It affects the validateKeyIdUrl() function in HttpSignatureService.php. The vulnerability allows unauthenticated attackers to bypass SSRF protections by using IPv6 transition addresses like 6to4, NAT64, or IPv4-compatible IPv6 formats. These addresses embed internal IPv4 targets, tricking the system into sending requests to internal hosts, loopback services, or cloud metadata endpoints.

Detection Guidance

To detect this vulnerability, check if your YesWiki instance is running a version before 4.6.7. Verify the version by inspecting the system or checking the software configuration. Additionally, monitor network traffic for outbound requests to cloud metadata services (169.254.169.254), loopback addresses (127.0.0.1), or RFC1918 private networks (e.g., 10.0.0.1) originating from the YesWiki application.

Impact Analysis

This vulnerability allows attackers to access internal services, loopback addresses (like 127.0.0.1), private networks (e.g., 10.0.0.1), or cloud metadata services (e.g., 169.254.169.254). It could lead to unauthorized data exposure, service enumeration, or further attacks if internal systems are compromised. Exploitation requires ActivityPub to be enabled on at least one Bazar form.

Compliance Impact

This vulnerability could potentially violate compliance with GDPR and HIPAA by enabling unauthorized access to internal services, cloud metadata, or loopback services. Unauthenticated attackers may exfiltrate sensitive data or interact with restricted systems, leading to breaches of confidentiality and integrity requirements under these regulations.

Mitigation Strategies

Immediately upgrade YesWiki to version 4.6.7 or later to address the SSRF vulnerability. If upgrading is not immediately possible, disable the ActivityPub feature on Bazar forms as the vulnerability requires it to be enabled. Additionally, implement network-level restrictions to block outbound requests to internal IP ranges and cloud metadata services.

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