CVE-2026-47883 Overview
CVE-2026-47883 is an open redirect vulnerability in the Spring Framework UrlHandlerFilter. The flaw affects filter variants in both Spring MVC and Spring WebFlux when configured with very broadly matching URL patterns. Attackers can craft URLs that cause the filter to redirect users to attacker-controlled destinations. Open redirects enable phishing campaigns and can facilitate credential theft by abusing trust in the vulnerable domain. The vulnerability affects Spring Framework versions 7.0.0 through 7.0.8 and 6.2.0 through 6.2.19.
Critical Impact
Broadly matching UrlHandlerFilter patterns allow attackers to redirect users to external domains, enabling phishing and social engineering attacks that leverage the trusted application origin.
Affected Products
- Spring Framework 7.0.0 - 7.0.8
- Spring Framework 6.2.0 - 6.2.19
- Applications using UrlHandlerFilter in Spring MVC or Spring WebFlux
Discovery Timeline
- 2026-08-27 - CVE-2026-47883 published to NVD
- 2026-08-27 - Last updated in NVD database
Technical Details for CVE-2026-47883
Vulnerability Analysis
The vulnerability resides in UrlHandlerFilter, a Spring Framework component that processes and normalizes incoming request URLs before passing them to downstream handlers. When applications register the filter with very broadly matching patterns, the filter processes URLs it was not intended to handle. Attackers can exploit this behavior to trigger HTTP redirects to arbitrary external destinations.
Open redirect vulnerabilities [CWE-601] weaken the trust boundary between a legitimate origin and untrusted content. An attacker crafts a link pointing to the vulnerable Spring application. The application returns a redirect response sending the victim to an attacker-controlled site. Because the initial URL displays a trusted domain, users are more likely to follow the link and submit credentials on the destination page.
Both Spring MVC (servlet-based) and Spring WebFlux (reactive) filter variants are affected. Consult the Spring Security Advisory for CVE-2026-47883 for full technical details.
Root Cause
The root cause is insufficient validation of URL patterns handled by UrlHandlerFilter. When developers configure the filter with wildcards or overly permissive matchers, the filter accepts request paths that resolve into redirect responses without validating whether the target host belongs to the application.
Attack Vector
An attacker constructs a URL targeting the vulnerable Spring application that includes an attacker-controlled redirect destination. The attacker delivers the link via email, chat, or a compromised website. When the victim clicks the link, UrlHandlerFilter matches the broad pattern and issues an HTTP redirect to the external destination. The exploitation requires no authentication and no interaction beyond a single click.
Detection Methods for CVE-2026-47883
Indicators of Compromise
- HTTP 3xx responses from the Spring application containing Location headers pointing to external domains not owned by the organization.
- Access log entries with unusual URL patterns targeting endpoints registered under UrlHandlerFilter.
- Referrer chains showing traffic flowing from the application to unrelated external hosts.
Detection Strategies
- Inventory all applications running Spring Framework 6.2.0-6.2.19 or 7.0.0-7.0.8 and identify those that register UrlHandlerFilter.
- Review filter registration code and configuration for broad URL patterns such as /** or wildcard-heavy matchers.
- Inspect web server and reverse proxy logs for outbound redirects to domains outside the organization's allowlist.
Monitoring Recommendations
- Alert on responses where the Location header host does not match the application's approved domain list.
- Monitor for spikes in 302 and 303 responses on endpoints served by UrlHandlerFilter.
- Correlate suspicious redirect activity with inbound campaigns to identify phishing infrastructure abusing the flaw.
How to Mitigate CVE-2026-47883
Immediate Actions Required
- Upgrade Spring Framework to a patched release above 6.2.19 or 7.0.8 as identified in the Spring Security Advisory.
- Audit every UrlHandlerFilter registration and narrow URL patterns to only the specific paths that require handling.
- Remove UrlHandlerFilter from applications that do not depend on its URL normalization behavior.
Patch Information
Pivotal has published fixed versions of Spring Framework addressing the open redirect behavior in UrlHandlerFilter. Refer to the Spring Security Advisory for CVE-2026-47883 for the exact patched release numbers and upgrade guidance.
Workarounds
- Restrict UrlHandlerFilter URL patterns to exact paths rather than wildcard matchers until the upgrade is complete.
- Implement a redirect allowlist at the reverse proxy or web application firewall layer to block Location headers pointing to untrusted hosts.
- Add server-side validation that rejects request parameters containing external URLs before they reach the filter.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
