CVE-2026-3260: 
Java vulnerability analysis and mitigation

CVE-2026-3260 is a Denial of Service (DoS) vulnerability in the Undertow web server caused by premature parsing of multipart/form-data content in HTTP GET requests. A remote, unauthenticated attacker can trigger resource exhaustion by sending crafted GET requests with multipart body content when the underlying application invokes parameter-parsing methods such as getParameterMap(). Affected products include Red Hat Undertow (as used in WildFly), JBoss Enterprise Application Platform 7.x and 8.x, Red Hat Single Sign-On 7.0, Red Hat Data Grid 8.0, Red Hat Fuse 7.0, Red Hat Process Automation 7.0, Red Hat Build of Apache Camel for Spring Boot 4.0, Red Hat Enterprise Linux 8/9/10, and IBM DevOps Test Performance (Rational Performance Tester). The vulnerability was reported on 2026-02-26 and publicly disclosed on 2026-03-24. It carries a CVSS v3.1 base score of 7.5 (High) per NVD, or 5.9 (Medium) per ENISA's scoring (Red Hat CVE, Red Hat Bugzilla).

The root cause is classified as CWE-770 (Allocation of Resources Without Limits or Throttling). Undertow incorrectly processes multipart/form-data content present in HTTP GET requests — a method that should not carry such a body — when the application calls parameter-parsing methods like getParameterMap() (e.g., in JSF-based applications). This premature parsing causes the server to allocate disk and memory resources to store the multipart content before any validation or size-limiting logic can intervene, enabling an attacker to exhaust server resources through repeated or oversized requests. No authentication or special privileges are required, and the attack complexity is low, making it straightforward to exploit from any network location (Red Hat Bugzilla, Red Hat CVE).

Successful exploitation results in resource exhaustion on the affected server, leading to a Denial of Service condition that degrades or completely disrupts availability of the hosted application. There is no impact on confidentiality or data integrity — the vulnerability is purely an availability issue. Applications built on Undertow that invoke getParameterMap() or similar parameter-parsing APIs are at risk, including those running on JBoss EAP, WildFly, Red Hat SSO, and IBM DevOps Test Performance (Red Hat CVE, IBM Advisory).

1. Reconnaissance: Identify internet-facing servers running Undertow-based applications (e.g., JBoss EAP, WildFly, Red Hat SSO) using tools like Shodan or Censys, or by fingerprinting HTTP response headers.
2. Identify vulnerable endpoint: Locate application endpoints that trigger parameter parsing (e.g., JSF pages or REST endpoints that call getParameterMap()), which can often be identified through application documentation or by observing normal application behavior.
3. Craft malicious GET request: Construct an HTTP GET request to the target endpoint with a Content-Type: multipart/form-data header and a large or repeated multipart body payload.
4. Send repeated requests: Flood the server with these crafted GET requests to continuously trigger premature multipart parsing and disk/memory allocation, exhausting server resources.
5. Achieve DoS: The server becomes unable to process legitimate requests due to resource exhaustion, resulting in service degradation or complete unavailability (Red Hat Bugzilla, Red Hat CVE).

• Network: Unusual volume of HTTP GET requests with Content-Type: multipart/form-data headers targeting application endpoints; large request body sizes associated with GET method traffic.
• Logs: Undertow/WildFly access logs showing repeated GET requests with multipart content types to parameter-parsing endpoints; disk I/O spikes correlated with incoming GET requests.
• File System: Unexpected temporary files created in the server's temp directory (e.g., /tmp or the JVM temp path) corresponding to multipart upload fragments from GET requests.
• Process/Resource: Abnormal disk usage growth or memory pressure on the JVM process hosting Undertow; increased garbage collection activity or OutOfMemoryError entries in server logs.

Red Hat has acknowledged the vulnerability and patches are in progress; users should monitor Red Hat's security advisories for fixed versions of JBoss EAP, Undertow, Red Hat SSO, and related products (Red Hat CVE). IBM has released an advisory for DevOps Test Performance (Rational Performance Tester) addressing this issue (IBM Advisory). As a workaround, consider deploying a web application firewall (WAF) or reverse proxy rule to reject HTTP GET requests that include a Content-Type: multipart/form-data header before they reach the Undertow server. Additionally, review application code to avoid invoking getParameterMap() or similar parameter-parsing methods in contexts where GET requests are expected, and apply rate limiting to reduce the impact of flooding attempts.

The vulnerability was tracked internally by Red Hat's Product Security team and reported via OSIDB on 2026-02-26, with a CC list of approximately 50 engineers and security personnel, indicating broad internal awareness (Red Hat Bugzilla). IBM issued a separate advisory for its affected DevOps Test Performance product, demonstrating downstream vendor impact (IBM Advisory). No notable public researcher commentary or significant social media discussion has been identified beyond standard CVE aggregator coverage.