Netty HttpPostRequestDecoder can OOM
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.
02 / AFFECTED SOFTWARE
Affected packages
158 explicit affected versions
201 explicit affected versions
03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
### Summary The `HttpPostRequestDecoder` can be tricked to accumulate data. I have spotted currently two attack vectors ### Details 1. 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. 2. 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.
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.
05 / REFERENCES
Further evidence
- https://gist.github.com/vietj/f558b8ea81ec6505f1e9a6ca283c9ae3
- https://github.com/netty/netty
- https://github.com/netty/netty/commit/0d0c6ed782d13d423586ad0c71737b2c7d02058c
- https://github.com/netty/netty/security/advisories/GHSA-5jpm-x58v-624v
- https://github.com/vietj/netty/tree/post-request-decoder
- https://lists.debian.org/debian-lts-announce/2024/06/msg00015.html
- https://nvd.nist.gov/vuln/detail/CVE-2024-29025
- https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/29xxx/CVE-2024-29025.json