In short
- CVE-2024-29025 is a MEDIUM (CVSS 5.3) vulnerability affecting io.netty:netty-codec-http, netty (netty).
- Chance of exploitation in the next 30 days (EPSS): 1.4%, higher than 72.1% of all vulnerabilities.
- Fix: update to 4.1.108.Final, 4.1.108 or later.
Description
Summary
The HttpPostRequestDecoder can be tricked to accumulate data. I have spotted currently two attack vectors
Details
- While the decoder can store items on the disk if configured so, there are no limits to the number of fields the form can have, an attacher can send a chunked post consisting of many small fields that will be accumulated in the
bodyListHttpData list.
- The decoder cumulates bytes in the
undecodedChunk buffer until it can decode a field, this field can cumulate data without limits
PoC
Here is a Netty branch that provides a fix + tests : https://github.com/vietj/netty/tree/post-request-decoder
Here is a reproducer with Vert.x (which uses this decoder) https://gist.github.com/vietj/f558b8ea81ec6505f1e9a6ca283c9ae3
Impact
Any Netty based HTTP server that uses the HttpPostRequestDecoder to decode a form.
NVD description
Netty is an asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers & clients. The `HttpPostRequestDecoder` can be tricked to accumulate data. While the decoder can store items on the disk if configured so, there are no limits to the number of fields the form can have, an attacher can send a chunked post consisting of many small fields that will be accumulated in the `bodyListHttpData` list. The decoder cumulates bytes in the `undecodedChunk` buffer until it can decode a field, this field can cumulate data without limits. This vulnerability is fixed in 4.1.108.Final.
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