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 vulnerability was found in Apache HTTP Server 2.4.34 to 2.4.38. When HTTP/2 was enabled for a http: host or H2Upgrade was enabled for h2 on a https: host, an Upgrade request from http/1.1 to http/2 that was not the first request on a connection could lead to a misconfiguration and crash. Server that never enabled the h2 protocol or that only enabled it for https: and did not set "H2Upgrade on" are unaffected by this issue.

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 9.2.26 and older, 9.3.25 and older, and 9.4.15 and older, the server is vulnerable to XSS conditions if a remote client USES a specially formatted URL against the DefaultServlet or ResourceHandler that is configured for showing a Listing of directory contents.

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.

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 Apache HTTP server versions 2.4.37 and prior, by sending request bodies in a slow loris way to plain resources, the h2 stream for that request unnecessarily occupied a server thread cleaning up that incoming data. This affects only HTTP/2 (mod_http2) connections.

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

Jetty through 9.4.x is prone to a timing channel in util/security/Password.java, which makes it easier for remote attackers to obtain access by observing elapsed times before rejection of incorrect passwords.