GHSA-9wj4-8h85-pgrw OctoPrint Vulnerable to Denial of Service through malformed HTTP request in OctoPrint

• PyPI OctoPrint: < 1.11.2 → fixed in 1.11.2

Impact OctoPrint versions up until and including 1.11.1 contain a vulnerability that allows any unauthenticated attacker to send a manipulated broken `multipart/form-data` request to OctoPrint and through that make the web server component become unresponsive. This could be used to effectively run a denial of service attack on the OctoPrint server. Patches The vulnerability has been patched in version 1.11.2. Workaround OctoPrint administrators are once more reminded to not make OctoPrint available on hostile networks (e.g. the internet), regardless of whether this vulnerability is patched or not. Details The issue can be triggered by a broken `multipart/form-data` request lacking an end boundary to any of OctoPrint's endpoints implemented through the `octoprint.server.util.tornado.UploadStorageFallbackHandler` request handler. The request handler will get stuck in an endless busy loop, looking for a part of the request that will never come. As Tornado is single-threaded, that will effectively block the whole web server. The fix adds detection of invalid requests like that and ensures they are handled gracefully with an HTTP 400 Bad Request response. Credits This vulnerability was discovered and responsibly disclosed to OctoPrint by Jacopo Tediosi.