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h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. In version 2.3.0-beta2 and prior, when h2o is configured to listen to multiple addresses or ports with each of them using different backend servers managed by multiple entities, a malicious backend entity that also has the opportunity to observe or inject packets exchanged between the client and h2o may misdirect HTTPS requests going to other backends and observe the contents of that HTTPS request being sent. The attack involves a victim client trying to resume a TLS connection and an attacker redirecting the packets to a different address or port than that intended by the client. The attacker must already have been configured by the administrator of h2o to act as a backend to one of the addresses or ports that the h2o instance listens to. Session IDs and tickets generated by h2o are not bound to information specific to the server address, port, or the X.509 certificate, and therefore it is possible for an attacker to force the victim connection to wrongfully resume against a different server address or port on which the same h2o instance is listening. Once a TLS session is misdirected to resume to a server address / port that is configured to use an attacker-controlled server as the backend, depending on the configuration, HTTPS requests from the victim client may be forwarded to the attacker's server. An H2O instance is vulnerable to this attack only if the instance is configured to listen to different addresses or ports using the listen directive at the host level and the instance is configured to connect to backend servers managed by multiple entities. A patch is available at commit 35760540337a47e5150da0f4a66a609fad2ef0ab. As a workaround, one may stop using using host-level listen directives in favor of global-level ones.
dena
HedgeDoc (formerly known as CodiMD) is an open-source collaborative markdown editor. An attacker can read arbitrary `.md` files from the server's filesystem due to an improper input validation, which results in the ability to perform a relative path traversal. To verify if you are affected, you can try to open the following URL: `http://localhost:3000/..%2F..%2FREADME#` (replace `http://localhost:3000` with your instance's base-URL e.g. `https://demo.hedgedoc.org/..%2F..%2FREADME#`). If you see a README page being rendered, you run an affected version. The attack works due the fact that the internal router passes the url-encoded alias to the `noteController.showNote`-function. This function passes the input directly to findNote() utility function, that will pass it on the the parseNoteId()-function, that tries to make sense out of the noteId/alias and check if a note already exists and if so, if a corresponding file on disk was updated. If no note exists the note creation-function is called, which pass this unvalidated alias, with a `.md` appended, into a path.join()-function which is read from the filesystem in the follow up routine and provides the pre-filled content of the new note. This allows an attacker to not only read arbitrary `.md` files from the filesystem, but also observes changes to them. The usefulness of this attack can be considered limited, since mainly markdown files are use the file-ending `.md` and all markdown files contained in the hedgedoc project, like the README, are public anyway. If other protections such as a chroot or container or proper file permissions are in place, this attack's usefulness is rather limited. On a reverse-proxy level one can force a URL-decode, which will prevent this attack because the router will not accept such a path.
hedgedoc