CVE-2026-10861 in MISP
Summary
by MITRE • 06/04/2026
An open redirect vulnerability existed in MISP UsersController::routeafterlogin() because the value stored in the pre_login_requested_url session key was used as the post-login redirect destination without sufficiently enforcing that it was a local application path.
An unauthenticated remote attacker could craft a link that causes a victim to visit a trusted MISP instance and, after successful authentication, be redirected to an attacker-controlled external URL. This could be abused to increase the credibility of phishing attacks, redirect users to counterfeit login pages, or deliver attacker-controlled content from an untrusted domain. CWE-601 describes this weakness as accepting user-controlled input that specifies an external link and using it in a redirect, with phishing as a common consequence.
The patch mitigates the issue by decoding and parsing the URL, rejecting URLs with a scheme, host, user component, missing or non-local path, and protocol-relative forms such as //example.com and /\example.com.
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Analysis
by VulDB Data Team • 06/04/2026
The open redirect vulnerability in MISP UsersController::routeafterlogin() represents a critical security flaw that allows attackers to manipulate post-authentication redirection behavior. This weakness stems from insufficient validation of the pre_login_requested_url session key, which is directly used as the redirect destination without proper sanitization. The vulnerability exists within the application's authentication flow where users are redirected to their originally requested page after successful login, creating an opportunity for malicious actors to exploit this mechanism for unauthorized redirection. The flaw specifically manifests when the application accepts user-supplied URLs without verifying their legitimacy or ensuring they point to internal application paths.
The technical implementation of this vulnerability allows unauthenticated remote attackers to construct malicious links that exploit the trust relationship between users and the MISP application. When a victim clicks such a crafted link and subsequently authenticates to the MISP instance, they are redirected to an attacker-controlled external domain rather than their intended destination. This behavior directly aligns with CWE-601 Open Redirect weakness classification, which explicitly identifies the acceptance of user-controlled input specifying external links as a dangerous practice that enables phishing attacks and other social engineering exploits. The vulnerability's impact extends beyond simple redirection as it leverages the application's trusted reputation to deliver malicious content or capture credentials from unsuspecting users.
The operational consequences of this vulnerability are severe and multifaceted in the cybersecurity landscape. Attackers can utilize this weakness to increase the credibility of phishing campaigns by making malicious redirects appear to originate from legitimate MISP instances, thereby bypassing user suspicion and security awareness. Additionally, the vulnerability enables redirection to counterfeit login pages that can harvest user credentials, or deliver attacker-controlled content from untrusted domains that may contain malware or other malicious payloads. This creates a significant risk for organizations using MISP for threat intelligence sharing and incident response, as compromised systems could become vectors for further attacks or data exfiltration. The attack vector is particularly dangerous because it requires only a single successful authentication to establish the malicious redirection chain, making it an attractive target for threat actors.
The patch implemented to address this vulnerability demonstrates a comprehensive approach to URL validation and sanitization. The solution involves decoding and parsing the URL structure to enforce strict validation criteria that reject potentially dangerous redirection attempts. The mitigation strategy specifically blocks URLs containing schemes such as http or https, host components that would direct users outside the application domain, user credentials within the URL, and path components that are missing or non-local to the application. The patch also addresses protocol-relative forms such as //example.com and /\example.com that could be used to bypass traditional validation checks. This approach aligns with security best practices for input validation and follows the principle of least privilege by ensuring that all redirect destinations must be strictly local to the application. The solution effectively addresses the root cause identified in CWE-601 by preventing the application from accepting and processing external URLs for redirection purposes, thereby eliminating the attack surface that enabled phishing and social engineering attacks.