CVE-2026-119545 in Forgejo
Summary
by MITRE • 10/30/2026
Forgejo through 15.0.11, 16.0.0 through 16.0.7, and 17.0.0 through 17.0.1 contains a server-side request forgery vulnerability that allows unauthenticated attackers to make the server issue requests by submitting arbitrary OpenID identifier URLs. Attackers can POST crafted identifiers to /user/login/openid to trigger blind discovery GET requests to loopback, cloud metadata, and internal addresses for port scanning and probing.
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Analysis
by VulDB Data Team • 10/30/2026
The identified vulnerability represents a critical Server-Side Request Forgery (SSRF) flaw within the Forgejo platform, affecting versions through 15.0.11, as well as release series 16.0.0 to 16.0.7 and 17.0.0 to 17.0.1. This security defect resides in the authentication subsystem, specifically within the endpoint responsible for handling OpenID Connect login requests at /user/login/openid. The core technical flaw stems from insufficient validation of user-supplied input when processing OpenID identifier URLs. Instead of restricting these identifiers to trusted domains or enforcing strict protocol constraints, the application blindly accepts arbitrary Uniform Resource Identifiers provided by unauthenticated users and instructs the server backend to initiate HTTP requests against them. This lack of sanitization allows an attacker to manipulate the destination address that the Forgejo server will contact on behalf of the user during the authentication discovery phase.
The operational impact of this vulnerability is severe due to its potential for blind exploitation and network reconnaissance. Because the initial request triggered by the forged identifier often results in a redirect or metadata fetch, attackers can leverage this behavior to perform port scanning and service probing against internal infrastructure that would otherwise be inaccessible from the public internet. By crafting specific OpenID identifiers pointing to loopback addresses such as 127.0.0.1 or localhost, an attacker can probe for services running on the local machine of the Forgejo server itself. Furthermore, by directing requests toward cloud metadata endpoints like those found at AWS EC2 instance metadata service URLs (e.g., http://169.254.169.254/latest/meta-data/), attackers may attempt to extract sensitive configuration data, temporary security credentials, or other environment-specific information that could facilitate further compromise of the underlying cloud infrastructure.
This vulnerability aligns with Common Weakness Enumeration (CWE) category CWE-918, which describes Server-Side Request Forgery where a web server makes requests based on user-supplied input without proper validation. Additionally, from an adversary perspective, this technique maps to MITRE ATT&CK tactic T1560, specifically the subtechnique of Data Staged via Cloud Infrastructure or internal network mapping techniques that rely on SSRF to pivot into restricted networks. The ability to probe internal addresses effectively turns the Forgejo server into a proxy for unauthorized network reconnaissance, potentially revealing the topology and services present within the organization's private network segments.
Mitigation strategies must prioritize immediate patching of all affected versions to 16.0.8 or later, where this input validation logic has been corrected. In environments where upgrading is not immediately feasible, administrators should implement strict web application firewall rules that block outbound requests from the Forgejo server IP address to internal RFC 1918 private ranges and cloud metadata endpoints unless explicitly required for legitimate business functions. Additionally, enforcing allow-listing of trusted OpenID providers at the configuration level can prevent arbitrary URL submission during the authentication flow. Regular auditing of network egress traffic originating from application servers is also recommended to detect any anomalous connection attempts that may indicate exploitation activity.