CVE-2026-85699 in Jina AI
Summary
by MITRE • 09/04/2026
jina-ai reader contains a server-side request forgery vulnerability where URL validation is performed only on the initial request but not re-applied to subsequent redirect hops. Attackers can craft a public URL that redirects to internal network addresses or cloud metadata endpoints, allowing the server to fetch and return the target's response body to the attacker.
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Analysis
by VulDB Data Team • 09/04/2026
The vulnerability identified in jina-ai reader represents a classic instance of Server-Side Request Forgery, specifically stemming from insufficient validation during HTTP redirect handling. This flaw arises because the application performs URL validation only on the initial request submitted by the user but fails to re-validate the final destination after one or more redirects occur. In standard web security practices, any change in the target host via a 3xx status code must trigger a fresh round of validation checks against an allowlist or denylist. By neglecting this step during redirect hops, the application effectively trusts external control over the request path without verifying that the final endpoint is authorized for access. This architectural oversight allows attackers to bypass initial security controls by leveraging intermediate servers that are permitted to make requests, thereby masking the true intent of the payload until it reaches its internal target.
From a technical perspective, this flaw aligns with CWE-918, which describes Server-Side Request Forgery (SSRF) where server-side code makes HTTP requests based on user-supplied input without proper validation of the resulting URL chain. The operational impact is severe because it enables an attacker to interact with internal network services that are typically isolated from public internet access. By crafting a maliciously constructed public URL that redirects to localhost, private IP ranges such as 10.x.x.x or 192.168.x.x, or cloud metadata endpoints like those found in AWS EC2 instance metadata service at 169.254.169.254, the attacker can force the server to fetch sensitive data. This capability allows for unauthorized access to internal APIs, retrieval of configuration files, and potentially the exfiltration of credentials or session tokens stored within cloud provider metadata services.
The exploitation scenario typically involves an attacker hosting a malicious page or link that issues an HTTP redirect pointing toward an internal resource. When the jina-ai reader processes this request, it validates the initial public URL, deems it safe, and proceeds to follow the redirect. Because the validation logic is not reapplied after the redirect response is received, the server blindly fetches content from the internal address specified in the Location header of the redirect response. The fetched data is then returned to the attacker through the reader's output mechanism. This behavior effectively turns the vulnerable service into a proxy for accessing restricted network segments, facilitating reconnaissance and further exploitation within the organization's infrastructure.
This vulnerability maps directly to MITRE ATT&CK technique T1598.002, which falls under Adversary-in-the-Middle and specifically involves Spoofing Resource. The attacker uses the vulnerable server as a pivot point to spoof requests from an internal source IP address or trusted domain, thereby bypassing network-level access controls that rely on source IP verification. Additionally, this behavior is consistent with CWE-400, where uncontrolled resource consumption might occur if the SSRF leads to infinite redirect loops, although in this specific case, the primary concern remains unauthorized data retrieval and internal network probing rather than denial of service.
Mitigation strategies must focus on implementing strict URL validation at every stage of request processing, including after redirects. Developers should maintain a comprehensive allowlist of permitted domains or IP ranges for outbound requests from the server side. It is critical to reject any redirect that points to private IP addresses, loopback interfaces, or cloud metadata endpoints unless explicitly required and secured by additional authentication mechanisms. Furthermore, implementing network-level controls such as egress filtering can provide an additional layer of defense by blocking outbound connections to internal subnets from public-facing servers. Regular security audits and static code analysis tools configured to detect SSRF patterns should be employed to identify similar vulnerabilities in other parts of the application logic before they can be exploited in production environments.