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

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). Vendors: Maven, 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
    # 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

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