CVE-2026-91750 in WeKnora
Summary
by MITRE • 09/15/2026
WeKnora before 0.7.0 fails to re-validate HTTP redirect targets in the POST /api/v1/knowledge-bases/:id/knowledge/url endpoint when downloading documents from user-supplied URLs. Authenticated attackers can bypass initial SSRF validation by supplying a public URL that redirects to internal network addresses, allowing access to internal services and cloud metadata.
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Analysis
by VulDB Data Team • 09/15/2026
The vulnerability identified in WeKnora versions prior to 0.7.0 represents a critical server-side request forgery flaw rooted in the improper handling of HTTP redirect responses during document ingestion processes. Specifically, the endpoint POST /api/v1/knowledge-bases/:id/knowledge/url is designed to allow authenticated users to supply URLs from which the system downloads and indexes documents for knowledge base construction. The core technical deficiency lies in the application's failure to re-validate the final destination of an HTTP request after following redirects. While the initial URL provided by the user may pass security checks, such as being a public domain or whitelisted address, the server blindly follows any Location headers returned during the redirect chain without performing subsequent validation on the new target URI. This architectural oversight creates a significant bypass mechanism for attackers who can manipulate the redirection process to point toward internal network resources that are otherwise inaccessible from the external internet.
From an operational perspective, this flaw allows authenticated adversaries to leverage the application's server-side capabilities to probe and access sensitive internal infrastructure. By crafting a malicious URL that redirects to localhost addresses or private IP ranges, such as 127.0.0.1 or 192.168.x.x, attackers can force WeKnora to make requests on their behalf. This capability effectively transforms the vulnerable application into an SSRF proxy, enabling unauthorized access to internal services running on ports that are not exposed publicly. Furthermore, this vulnerability facilitates attacks against cloud metadata endpoints, such as those found in AWS EC2 instances at 169.254.169.254 or similar endpoints in other cloud providers like Azure and GCP. Through these requests, attackers can potentially retrieve instance identity credentials, IAM roles, and configuration data, which may lead to further compromise of the underlying infrastructure and escalation of privileges within the cloud environment.
This vulnerability aligns with Common Weakness Enumeration CWE-918, commonly known as Server-Side Request Forgery (SSRF), specifically under subcategories involving insufficient validation of redirect targets. In terms of offensive security frameworks, this exploit maps to MITRE ATT&CK technique T1571, which covers Non-Standard Ports and protocols used in SSRF attacks, although the primary vector here is standard HTTP redirects rather than port manipulation. The attack also relates to T1098, specifically SSH Authorized Key Manipulation if cloud metadata keys are exfiltrated for subsequent access, or more broadly to reconnaissance activities aimed at mapping internal network topology via proxying requests through a trusted application server.
To mitigate this risk, immediate action is required by upgrading WeKnora to version 0.7.0 or later where the redirect validation logic has been corrected. In environments where an upgrade is not immediately feasible, defensive measures should include implementing strict allow-lists for both initial URLs and any subsequent redirected targets at a network level using firewalls or reverse proxies that inspect outbound traffic from the application server. Additionally, developers must ensure that all HTTP clients used in backend services enforce strict redirect policies, such as disabling automatic redirects entirely and manually handling them with rigorous validation of each hop's destination against internal IP ranges and cloud metadata endpoints. Implementing egress filtering rules to block requests originating from the WeKnora service account to private RFC1918 address spaces is also a critical compensating control that can significantly reduce the blast radius of this vulnerability even if application-level fixes are delayed.