---
id: "CVE-2026-116734"
kind: "vulnerability"
aliases: ["CVE-2026-116734"]
title: "flatcc: integer overflow in FlatBuffers header check crashes 32-bit builds"
severity: "medium"
cvss: 6.3
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["32-bit", "c", "flatbuffers", "flatcc", "package"]
not_affected_if: ["64-bit-only-builds", "trusted-input-only"]
published_at: "2026-10-26T22:16:57+00:00"
first_seen_at: "2026-10-26T22:25:34+00:00"
updated_at: "2026-10-26T22:27:57+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-116734", "first_seen_at": "2026-10-26T22:25:34+00:00"}]
---

# flatcc: integer overflow in FlatBuffers header check crashes 32-bit builds

flatcc through 0.6.4 has a dead-code overflow guard in its FlatBuffers verifier's check_header function. On 32-bit builds, a crafted buffer offset wraps the bounds check and causes an out-of-bounds read before the buffer, which crashes the process.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- unknown

## Fix

- unknown

## Timeline

- 2026-10-26T22:25:34+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-116734

## From the sources

flatcc through 0.6.4 contains an integer overflow vulnerability in the check_header function of the FlatBuffers verifier because its overflow guard is dead code. On 32-bit builds, attackers can supply a crafted buffer offset that wraps the bounds check, causing an out-of-bounds read before the buffer and crashing the process.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_