# CVE-2026-61799: Netty Binary HTTP parser integer overflow in varint parsing

Source: https://junglewise.ai/threats/cve-2026-61799-netty-binary-http-parser-integer-overflow-in-varint-parsing  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-20. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-61799 · Severity: medium · CVSS 5.3 · Published 2026-08-20

Netty's Binary HTTP decoder library contains an integer overflow vulnerability in its varint length parser. When processing HTTP message headers encoded in the binary HTTP format, the parser uses 32-bit integers to track cumulative byte offsets while adding attacker-supplied 64-bit length values, causing wraparound and negative indices. A remote attacker can crash individual connections by sending a tiny (15-byte) malformed message, leading to denial of service for any application accepting binary HTTP traffic from untrusted sources.

Technologies: [io.netty.incubator:netty-incubator-codec-bhttp (Maven)](https://junglewise.ai/threats/technologies/io-netty-incubator-netty-incubator-codec-bhttp). Vendors: [Maven](https://junglewise.ai/threats/vendors/maven), [Netty](https://junglewise.ai/threats/vendors/netty).

## Quick answers

**Is CVE-2026-61799 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-61799 being exploited in the wild.

**How severe is CVE-2026-61799?** Medium severity, with a CVSS score of 5.3, published 20 August 2026.

**Which products and versions are affected?** io.netty.incubator:netty-incubator-codec-bhttp (Maven) <= 0.0.22.Final, ECOSYSTEM:introduced=0,fixed=0.0.23.Final; Netty-Incubator-Codec-Bhttp <= 0.0.22.Final.

**Is there a fix for CVE-2026-61799?** Yes. io.netty.incubator:netty-incubator-codec-bhttp (Maven): upgrade to 0.0.23.Final or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-61799 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-61799?** Check whether you run io.netty.incubator:netty-incubator-codec-bhttp (Maven) or Netty-Incubator-Codec-Bhttp at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- io.netty.incubator:netty-incubator-codec-bhttp (Maven): upgrade to 0.0.23.Final or later

  ```sh
  # set io.netty.incubator:netty-incubator-codec-bhttp to 0.0.23.Final in your pom.xml or build.gradle
  ```


## Technical details

The vulnerability exists in io.netty.incubator:netty-incubator-codec-bhttp's BinaryHttpParser class, specifically in methods readRequestHead(), readFieldLine(), and getIndeterminateLength(). These methods declare cumulative offset counters as 32-bit signed integers (int sumBytes) and then perform compound assignment operations with 64-bit protocol lengths (long values), which Java narrows back to int. A length value of 2^31 (0x80000000) causes sumBytes to wrap negative, bypassing the bounds check (sumBytes >= in.readableBytes()), and subsequently triggering an unchecked ArrayIndexOutOfBoundsException or IndexOutOfBoundsException when computing buffer indices. The vulnerability requires network-reachable access to an application exposing BinaryHttpDecoder, with no authentication required. An attacker can trigger repeated exceptions to sustain denial of service. The fix, available in version 0.0.23.Final, uses 64-bit arithmetic throughout and validates lengths before narrowing to 32-bit indices.

## Affected products

- Netty netty-incubator-codec-bhttp <= 0.0.22.Final

## Identifiers

- CVE-2026-61799
- GHSA-pgrf-4654-3gq8

## Timeline

- 2026-08-20: disclosed: Advisory published to GitHub Advisory Database
- 2026-08-20: patched: Fix released in version 0.0.23.Final

## References

- [https://api.github.com/users/sondt99](https://api.github.com/users/sondt99)
- [https://github.com/sondt99](https://github.com/sondt99)
- [https://api.github.com/users/sondt99/gists%7B/gist_id%7D](https://api.github.com/users/sondt99/gists%7B/gist_id%7D)
- [https://api.github.com/users/sondt99/repos](https://api.github.com/users/sondt99/repos)
- [https://avatars.githubusercontent.com/u/87920408?v=4](https://avatars.githubusercontent.com/u/87920408?v=4)
- [https://api.github.com/users/sondt99/events%7B/privacy%7D](https://api.github.com/users/sondt99/events%7B/privacy%7D)

## Related threats

- [Netty Incubator OHTTP BinaryHttpParser infinite loop DoS](https://junglewise.ai/threats/cve-2026-63202-netty-incubator-ohttp-binaryhttpparser-infinite-loop-dos)
- [Netty Incubator OHTTP unbounded variable-length field buffering](https://junglewise.ai/threats/cve-2026-61827-netty-incubator-ohttp-unbounded-variable-length-field-buffering)
- [Netty netty-incubator-codec-bhttp infinite loop in field section parser](https://junglewise.ai/threats/cve-2026-63124-netty-netty-incubator-codec-bhttp-infinite-loop-in-field-section)
- [Absent Input Validation in BinaryHttpParser](https://junglewise.ai/threats/cve-2024-40642-absent-input-validation-in-binaryhttpparser)