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Vendor redhat✕Product undertow✕
Overview 34 matches · 0 protected · 0 exploited · 0 CISA KEV · 0 public PoC · 0 EPSS ≥ 0.5
34matches 0protected0.0% 0exploited0.0% 0CISA KEV0.0% 0public PoC0.0% 0EPSS ≥ 0.50.0%
Protected by Waratek 0 0.0% Rule in development 0 0.0% Mitigation candidate 0 0.0% No exploit published 34 100.0%
Critical 4 11.8% High 18 52.9% Medium 12 35.3% Low 0 0.0% None 0 0.0% Unknown 0 0.0%
blocked by ARMR today 0 0.0% partly blocked 0 0.0% not blocked 34 100.0% not established 0 0.0% unrecorded 0 0.0%
Exploited 0 0.0% Working exploit published 0 0.0% Proof of concept only 1 2.9% Forecast only 0 0.0% No public exploit 33 97.1%
split by peak 8 / year
No exploit published: 34 Medium: 12High: 18Critical: 4 not blocked: 34 No public exploit: 33Proof of concept only: 1
20188 No exploit published8 High2 Medium6 not blocked8 No public exploit8 20191 No exploit published1 High1 not blocked1 No public exploit1 20205 No exploit published5 High3 Medium2 not blocked5 No public exploit5 20213 No exploit published3 High2 Medium1 not blocked3 No public exploit3 20228 No exploit published8 High5 Medium3 not blocked8 No public exploit8 20234 No exploit published4 High4 not blocked4 No public exploit4 20240 20251 No exploit published1 High1 not blocked1 No public exploit1 20264 No exploit published4 Critical4 not blocked4 Proof of concept only1 No public exploit3
201820192020202120222023202420252026
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CVE Severity Published▾ Status Exploitation Description
CVE-2026-28369 Critical 2026-03-27 No exploit published No public exploit 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.
CVE-2026-28368 Critical 2026-03-27 No exploit published No public exploit 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.
CVE-2026-28367 Critical 2026-03-27 No exploit published No public exploit 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.
CVE-2025-12543 Critical 2026-01-07 No exploit published Proof of concept only 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.
CVE-2025-9784 High 2025-09-02 No exploit published No public exploit 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).
CVE-2023-5379 High 2023-12-12 No exploit published No public exploit A flaw was found in Undertow. When an AJP request is sent that exceeds the max-header-size attribute in ajp-listener, JBoss EAP is marked in an error state by mod_cluster in httpd, causing JBoss EAP to close the TCP connection without returning an AJP response. This happens because mod_proxy_cluster marks the JBoss EAP instance as an error worker when the TCP connection is closed from the backend after sending the AJP request without receiving an AJP response, and stops forwarding. This issue could allow a malicious user could to repeatedly send requests that exceed the max-header-size, causing a Denial of Service (DoS).
CVE-2023-3223 High 2023-09-27 No exploit published No public exploit A flaw was found in undertow. Servlets annotated with @MultipartConfig may cause an OutOfMemoryError due to large multipart content. This may allow unauthorized users to cause remote Denial of Service (DoS) attack. If the server uses fileSizeThreshold to limit the file size, it's possible to bypass the limit by setting the file name in the request to null.
CVE-2023-1108 High 2023-09-14 No exploit published No public exploit 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.
CVE-2022-4492 High 2023-02-23 No exploit published No public exploit The undertow client is not checking the server identity presented by the server certificate in https connections. This is a compulsory step (at least it should be performed by default) in https and in http/2. I would add it to any TLS client protocol.
CVE-2022-2764 Medium 2022-09-01 No exploit published No public exploit A flaw was found in Undertow. Denial of service can be achieved as Undertow server waits for the LAST_CHUNK forever for EJB invocations.
CVE-2022-1319 High 2022-08-31 No exploit published No public exploit A flaw was found in Undertow. For an AJP 400 response, EAP 7 is improperly sending two response packets, and those packets have the reuse flag set even though JBoss EAP closes the connection. A failure occurs when the connection is reused after a 400 by CPING since it reads in the second SEND_HEADERS response packet instead of a CPONG.
CVE-2022-1259 High 2022-08-31 No exploit published No public exploit A flaw was found in Undertow. A potential security issue in flow control handling by the browser over HTTP/2 may cause overhead or a denial of service in the server. This flaw exists because of an incomplete fix for CVE-2021-3629.
CVE-2021-3859 High 2022-08-26 No exploit published No public exploit A flaw was found in Undertow that tripped the client-side invocation timeout with certain calls made over HTTP2. This flaw allows an attacker to carry out denial of service attacks.
CVE-2021-3690 High 2022-08-23 No exploit published No public exploit A flaw was found in Undertow. A buffer leak on the incoming WebSocket PONG message may lead to memory exhaustion. This flaw allows an attacker to cause a denial of service. The highest threat from this vulnerability is availability.
CVE-2022-2053 High 2022-08-05 No exploit published No public exploit When a POST request comes through AJP and the request exceeds the max-post-size limit (maxEntitySize), Undertow's AjpServerRequestConduit implementation closes a connection without sending any response to the client/proxy. This behavior results in that a front-end proxy marking the backend worker (application server) as an error state and not forward requests to the worker for a while. In mod_cluster, this continues until the next STATUS request (10 seconds intervals) from the application server updates the server state. So, in the worst case, it can result in "All workers are in error state" and mod_cluster responds "503 Service Unavailable" for a while (up to 10 seconds). In mod_proxy_balancer, it does not forward requests to the worker until the "retry" timeout passes. However, luckily, mod_proxy_balancer has "forcerecovery" setting (On by default; this parameter can force the immediate recovery of all workers without considering the retry parameter of the workers if all workers of a balancer are in error state.). So, unlike mod_cluster, mod_proxy_balancer does not result in responding "503 Service Unavailable". An attacker could use this behavior to send a malicious request and trigger server errors, resulting in DoS (denial of service). This flaw was fixed in Undertow 2.2.19.Final, Undertow 2.3.0.Alpha2.
CVE-2021-3629 Medium 2022-05-24 No exploit published No public exploit A flaw was found in Undertow. A potential security issue in flow control handling by the browser over http/2 may potentially cause overhead or a denial of service in the server. The highest threat from this vulnerability is availability. This flaw affects Undertow versions prior to 2.0.40.Final and prior to 2.2.11.Final.
CVE-2021-3597 Medium 2022-05-24 No exploit published No public exploit A flaw was found in undertow. The HTTP2SourceChannel fails to write the final frame under some circumstances, resulting in a denial of service. The highest threat from this vulnerability is availability. This flaw affects Undertow versions prior to 2.0.35.SP1, prior to 2.2.6.SP1, prior to 2.2.7.SP1, prior to 2.0.36.SP1, prior to 2.2.9.Final and prior to 2.0.39.Final.
CVE-2019-19343 High 2021-03-23 No exploit published No public exploit A flaw was found in Undertow when using Remoting as shipped in Red Hat Jboss EAP before version 7.2.4. A memory leak in HttpOpenListener due to holding remote connections indefinitely may lead to denial of service. Versions before undertow 2.0.25.SP1 and jboss-remoting 5.0.14.SP1 are believed to be vulnerable.
CVE-2021-20220 Medium 2021-02-23 No exploit published No public exploit A flaw was found in Undertow. A regression in the fix for CVE-2020-10687 was found. HTTP request smuggling related to CVE-2017-2666 is possible against HTTP/1.x and HTTP/2 due to permitting invalid characters in an HTTP request. This flaw allows an attacker to poison a web-cache, perform an XSS attack, or obtain sensitive information from request other than their own. The highest threat from this vulnerability is to data confidentiality and integrity.
CVE-2020-27782 High 2021-02-23 No exploit published No public exploit A flaw was found in the Undertow AJP connector. Malicious requests and abrupt connection closes could be triggered by an attacker using query strings with non-RFC compliant characters resulting in a denial of service. The highest threat from this vulnerability is to system availability. This affects Undertow 2.1.5.SP1, 2.0.33.SP2, and 2.2.3.SP1.
CVE-2020-10687 Medium 2020-09-23 No exploit published No public exploit A flaw was discovered in all versions of Undertow before Undertow 2.2.0.Final, where HTTP request smuggling related to CVE-2017-2666 is possible against HTTP/1.x and HTTP/2 due to permitting invalid characters in an HTTP request. This flaw allows an attacker to poison a web-cache, perform an XSS attack, or obtain sensitive information from request other than their own.
CVE-2020-10705 High 2020-06-10 No exploit published No public exploit A flaw was discovered in Undertow in versions before Undertow 2.1.1.Final where certain requests to the "Expect: 100-continue" header may cause an out of memory error. This flaw may potentially lead to a denial of service.
CVE-2020-10719 Medium 2020-05-26 No exploit published No public exploit A flaw was found in Undertow in versions before 2.1.1.Final, regarding the processing of invalid HTTP requests with large chunk sizes. This flaw allows an attacker to take advantage of HTTP request smuggling.
CVE-2020-1757 High 2020-04-21 No exploit published No public exploit A flaw was found in all undertow-2.x.x SP1 versions prior to undertow-2.0.30.SP1, all undertow-1.x.x and undertow-2.x.x versions prior to undertow-2.1.0.Final, where the Servlet container causes servletPath to normalize incorrectly by truncating the path after semicolon which may lead to an application mapping resulting in the security bypass.
CVE-2019-14888 High 2020-01-23 No exploit published No public exploit A vulnerability was found in the Undertow HTTP server in versions before 2.0.28.SP1 when listening on HTTPS. An attacker can target the HTTPS port to carry out a Denial Of Service (DOS) to make the service unavailable on SSL.
CVE-2019-10184 High 2019-07-25 No exploit published No public exploit undertow before version 2.0.23.Final is vulnerable to an information leak issue. Web apps may have their directory structures predicted through requests without trailing slashes via the api.
CVE-2018-14642 Medium 2018-09-18 No exploit published No public exploit An information leak vulnerability was found in Undertow. If all headers are not written out in the first write() call then the code that handles flushing the buffer will always write out the full contents of the writevBuffer buffer, which may contain data from previous requests.
CVE-2018-1114 Medium 2018-09-11 No exploit published No public exploit It was found that URLResource.getLastModified() in Undertow closes the file descriptors only when they are finalized which can cause file descriptors to exhaust. This leads to a file handler leak.
CVE-2017-2670 High 2018-07-27 No exploit published No public exploit It was found in Undertow before 1.3.28 that with non-clean TCP close, the Websocket server gets into infinite loop on every IO thread, effectively causing DoS.
CVE-2017-2666 Medium 2018-07-27 No exploit published No public exploit It was discovered in Undertow that the code that parsed the HTTP request line permitted invalid characters. This could be exploited, in conjunction with a proxy that also permitted the invalid characters but with a different interpretation, to inject data into the HTTP response. By manipulating the HTTP response the attacker could poison a web-cache, perform an XSS attack, or obtain sensitive information from requests other than their own.
CVE-2017-12165 High 2018-07-27 No exploit published No public exploit It was discovered that Undertow before 1.4.17, 1.3.31 and 2.0.0 processes http request headers with unusual whitespaces which can cause possible http request smuggling.
CVE-2018-1067 Medium 2018-05-21 No exploit published No public exploit In Undertow before versions 7.1.2.CR1, 7.1.2.GA it was found that the fix for CVE-2016-4993 was incomplete and Undertow web server is vulnerable to the injection of arbitrary HTTP headers, and also response splitting, due to insufficient sanitization and validation of user input before the input is used as part of an HTTP header value.
CVE-2017-12196 Medium 2018-04-18 No exploit published No public exploit undertow before versions 1.4.18.SP1, 2.0.2.Final, 1.4.24.Final was found vulnerable when using Digest authentication, the server does not ensure that the value of URI in the Authorization header matches the URI in HTTP request line. This allows the attacker to cause a MITM attack and access the desired content on the server.
CVE-2017-7559 Medium 2018-01-10 No exploit published No public exploit In Undertow 2.x before 2.0.0.Alpha2, 1.4.x before 1.4.17.Final, and 1.3.x before 1.3.31.Final, it was found that the fix for CVE-2017-2666 was incomplete and invalid characters are still allowed in the query string and path parameters. This could be exploited, in conjunction with a proxy that also permitted the invalid characters but with a different interpretation, to inject data into the HTTP response. By manipulating the HTTP response the attacker could poison a web-cache, perform an XSS attack, or obtain sensitive information from requests other than their own.