A flaw was found in Undertow. When Undertow receives an HTTP request where the first header line starts with one or more spaces, it incorrectly processes the request by stripping these leading spaces. This behavior, which violates HTTP standards, can be exploited by a remote attacker to perform request smuggling. Request smuggling allows an attacker to bypass security mechanisms, access restricted information, or manipulate web caches, potentially leading to unauthorized actions or data exposure.
CVSS Score
8.7
EPSS Score
0.007
Published
2026-03-27
A flaw was found in Undertow. A remote attacker can exploit this vulnerability by sending `\r\r\r` as a header block terminator. This can be used for request smuggling with certain proxy servers, such as older versions of Apache Traffic Server and Google Cloud Classic Application Load Balancer, potentially leading to unauthorized access or manipulation of web requests.
CVSS Score
8.7
EPSS Score
0.007
Published
2026-03-27
A flaw was found in Undertow. This vulnerability allows a remote attacker to construct specially crafted requests where header names are parsed differently by Undertow compared to upstream proxies. This discrepancy in header interpretation can be exploited to launch request smuggling attacks, potentially bypassing security controls and accessing unauthorized resources.
CVSS Score
8.7
EPSS Score
0.007
Published
2026-03-27
A flaw was found in Undertow. A remote attacker could exploit this vulnerability by sending an HTTP GET request containing multipart/form-data content. If the underlying application processes parameters using methods like `getParameterMap()`, the server prematurely parses and stores this content to disk. This could lead to resource exhaustion, potentially resulting in a Denial of Service (DoS).
CVSS Score
5.9
EPSS Score
0.004
Published
2026-03-24
A container privilege escalation flaw was found in certain Fuse images. This issue stems from the /etc/passwd file being created with group-writable permissions during build time. In certain conditions, an attacker who can execute commands within an affected container, even as a non-root user, can leverage their membership in the root group to modify the /etc/passwd file. This could allow the attacker to add a new user with any arbitrary UID, including UID 0, leading to full root privileges within the container.
CVSS Score
6.4
EPSS Score
0.002
Published
2026-03-13
A flaw was found in the Undertow HTTP server core, which is used in WildFly, JBoss EAP, and other Java applications. The Undertow library fails to properly validate the Host header in incoming HTTP requests.As a result, requests containing malformed or malicious Host headers are processed without rejection, enabling attackers to poison caches, perform internal network scans, or hijack user sessions.
CVSS Score
9.6
EPSS Score
0.012
Published
2026-01-07
A flaw was found in Undertow where malformed client requests can trigger server-side stream resets without triggering abuse counters. This issue, referred to as the "MadeYouReset" attack, allows malicious clients to induce excessive server workload by repeatedly causing server-side stream aborts. While not a protocol bug, this highlights a common implementation weakness that can be exploited to cause a denial of service (DoS).
CVSS Score
7.5
EPSS Score
0.022
Published
2025-09-02
A vulnerability was found in Undertow. This vulnerability impacts a server that supports the wildfly-http-client protocol. Whenever a malicious user opens and closes a connection with the HTTP port of the server and then closes the connection immediately, the server will end with both memory and open file limits exhausted at some point, depending on the amount of memory available.
At HTTP upgrade to remoting, the WriteTimeoutStreamSinkConduit leaks connections if RemotingConnection is closed by Remoting ServerConnectionOpenListener. Because the remoting connection originates in Undertow as part of the HTTP upgrade, there is an external layer to the remoting connection. This connection is unaware of the outermost layer when closing the connection during the connection opening procedure. Hence, the Undertow WriteTimeoutStreamSinkConduit is not notified of the closed connection in this scenario. Because WriteTimeoutStreamSinkConduit creates a timeout task, the whole dependency tree leaks via that task, which is added to XNIO WorkerThread. So, the workerThread points to the Undertow conduit, which contains the connections and causes the leak.
CVSS Score
7.5
EPSS Score
0.046
Published
2024-02-19
A flaw was found in undertow. This issue makes achieving a denial of service possible due to an unexpected handshake status updated in SslConduit, where the loop never terminates.
CVSS Score
7.5
EPSS Score
0.018
Published
2023-09-14
A arbitrary code execution flaw was found in the Fabric 8 Kubernetes client affecting versions 5.0.0-beta-1 and above. Due to an improperly configured YAML parsing, this will allow a local and privileged attacker to supply malicious YAML.
CVSS Score
6.7
EPSS Score
0.003
Published
2022-08-24
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