CVE-2026-44915 Overview
CVE-2026-44915 is an open redirect vulnerability [CWE-601] affecting Apache APISIX, an open-source cloud-native API gateway. The flaw resides in the default configuration of the cas-auth plugin, which handles Central Authentication Service (CAS) integration. Attackers can craft URLs that abuse the gateway to redirect victims to attacker-controlled sites, enabling phishing campaigns and credential theft against users who trust the APISIX domain.
The issue affects Apache APISIX releases from 3.0.0 through 3.16.0. The Apache APISIX project has released version 3.17.0 to address the flaw.
Critical Impact
Adversaries can leverage trusted Apache APISIX gateway URLs to redirect authenticated users to malicious sites, facilitating credential theft through phishing.
Affected Products
- Apache APISIX 3.0.0 through 3.16.0
- Deployments using the cas-auth plugin with default configuration
- API gateway environments integrated with CAS-based single sign-on
Discovery Timeline
- 2026-06-19 - CVE-2026-44915 published to NVD
- 2026-06-23 - Last updated in NVD database
Technical Details for CVE-2026-44915
Vulnerability Analysis
Apache APISIX provides the cas-auth plugin to delegate authentication to a CAS server. During the CAS authentication flow, the plugin processes redirect parameters to return users to their originally requested resource after successful login. The default configuration does not adequately validate the destination URL, permitting redirection to arbitrary external domains.
An attacker exploits the flaw by distributing links that appear to originate from a trusted APISIX-fronted application. When a victim clicks the link, the gateway initiates the CAS flow and ultimately redirects the browser to an attacker-controlled domain. The attacker-controlled page can mimic the legitimate login interface to harvest credentials or deliver further payloads.
Root Cause
The root cause is missing or insufficient allowlist validation of redirect destinations within the cas-auth plugin's default configuration. The plugin trusts client-supplied redirect parameters without verifying that the target matches an approved origin, satisfying the conditions for [CWE-601] URL Redirection to Untrusted Site.
Attack Vector
Exploitation requires user interaction. The attacker must convince a victim to click a crafted URL pointing to the vulnerable APISIX endpoint. No authentication or elevated privileges are required on the attacker side. Because the malicious link begins with the legitimate gateway hostname, standard URL-inspection defenses and email security filters are less likely to flag it.
No verified public proof-of-concept code is available. Refer to the Apache mailing list advisory and the Openwall OSS-Security post for vendor details.
Detection Methods for CVE-2026-44915
Indicators of Compromise
- Gateway access logs containing cas-auth redirect parameters that reference external hostnames not on the organization's allowlist.
- Unusual outbound HTTP 302 responses from APISIX with Location headers pointing to domains unrelated to the organization.
- User reports of unexpected login prompts or redirection after clicking links to internal APISIX-fronted services.
Detection Strategies
- Inspect APISIX access logs for query parameters carrying URLs and compare destination domains against an approved list of CAS service URLs.
- Deploy web application firewall rules that flag redirect parameters whose hostnames do not match internal domains.
- Correlate authentication events from the CAS server with downstream redirects observed at the APISIX layer to identify mismatches.
Monitoring Recommendations
- Forward APISIX and CAS authentication logs to a centralized analytics platform for continuous review of redirect destinations.
- Alert on spikes in redirect responses originating from cas-auth-enabled routes.
- Monitor DNS and proxy egress data for newly registered or low-reputation domains receiving traffic immediately after APISIX redirects.
How to Mitigate CVE-2026-44915
Immediate Actions Required
- Upgrade Apache APISIX to version 3.17.0 or later on all gateway nodes.
- Audit cas-auth plugin configurations and explicitly define trusted redirect targets where supported.
- Review recent access logs for evidence of redirect abuse and notify any affected users to reset credentials.
Patch Information
The Apache APISIX maintainers released version 3.17.0, which corrects the default behavior of the cas-auth plugin. Administrators should consult the official Apache APISIX advisory for upgrade guidance and verify plugin configurations after deployment.
Workarounds
- If upgrading immediately is not feasible, disable the cas-auth plugin on routes that do not strictly require it.
- Place a reverse proxy or web application firewall in front of APISIX to validate redirect parameters against an allowlist of approved destinations.
- Educate users about phishing risks and instruct them to verify the final destination domain after authentication redirects.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
