There's a vulnerability within the Apache Xerces Java (XercesJ) XML parser when handling specially crafted XML document payloads. This causes, the XercesJ XML parser to wait in an infinite loop, which may sometimes consume system resources for prolonged duration. This vulnerability is present within XercesJ version 2.12.1 and the previous versions.

A carefully crafted request body can cause a buffer overflow in the mod_lua multipart parser (r:parsebody() called from Lua scripts). The Apache httpd team is not aware of an exploit for the vulnerabilty though it might be possible to craft one. This issue affects Apache HTTP Server 2.4.51 and earlier.

A crafted URI sent to httpd configured as a forward proxy (ProxyRequests on) can cause a crash (NULL pointer dereference) or, for configurations mixing forward and reverse proxy declarations, can allow for requests to be directed to a declared Unix Domain Socket endpoint (Server Side Request Forgery). This issue affects Apache HTTP Server 2.4.7 up to 2.4.51 (included).

Apache Log4j2 versions 2.0-alpha1 through 2.16.0 (excluding 2.12.3 and 2.3.1) did not protect from uncontrolled recursion from self-referential lookups. This allows an attacker with control over Thread Context Map data to cause a denial of service when a crafted string is interpreted. This issue was fixed in Log4j 2.17.0, 2.12.3, and 2.3.1.

In Apache HTTP Server 2.4.32-2.4.39, when mod_remoteip was configured to use a trusted intermediary proxy server using the "PROXY" protocol, a specially crafted PROXY header could trigger a stack buffer overflow or NULL pointer deference. This vulnerability could only be triggered by a trusted proxy and not by untrusted HTTP clients.

In Apache HTTP Server 2.4.0-2.4.39, a limited cross-site scripting issue was reported affecting the mod_proxy error page. An attacker could cause the link on the error page to be malformed and instead point to a page of their choice. This would only be exploitable where a server was set up with proxying enabled but was misconfigured in such a way that the Proxy Error page was displayed.

In Apache HTTP Server 2.4.18-2.4.39, using fuzzed network input, the http/2 session handling could be made to read memory after being freed, during connection shutdown.

Some HTTP/2 implementations are vulnerable to unconstrained interal data buffering, potentially leading to a denial of service. The attacker opens the HTTP/2 window so the peer can send without constraint; however, they leave the TCP window closed so the peer cannot actually write (many of) the bytes on the wire. The attacker then sends a stream of requests for a large response object. Depending on how the servers queue the responses, this can consume excess memory, CPU, or both.

A Server Side Request Forgery (SSRF) vulnerability affected the Apache Axis 1.4 distribution that was last released in 2006. Security and bug commits commits continue in the projects Axis 1.x Subversion repository, legacy users are encouraged to build from source. The successor to Axis 1.x is Axis2, the latest version is 1.7.9 and is not vulnerable to this issue.

In Eclipse Jetty version 7.x, 8.x, 9.2.27 and older, 9.3.26 and older, and 9.4.16 and older, the server running on any OS and Jetty version combination will reveal the configured fully qualified directory base resource location on the output of the 404 error for not finding a Context that matches the requested path. The default server behavior on jetty-distribution and jetty-home will include at the end of the Handler tree a DefaultHandler, which is responsible for reporting this 404 error, it presents the various configured contexts as HTML for users to click through to. This produced HTML includes output that contains the configured fully qualified directory base resource location for each context.

In Eclipse Jetty version 9.2.27, 9.3.26, and 9.4.16, the server running on Windows is vulnerable to exposure of the fully qualified Base Resource directory name on Windows to a remote client when it is configured for showing a Listing of directory contents. This information reveal is restricted to only the content in the configured base resource directories.

Apache Axis 1.x up to and including 1.4 is vulnerable to a cross-site scripting (XSS) attack in the default servlet/services.