---
id: CVE-2026-107909
title: >-
  A heap-based out-of-bounds write in the ws_read_frame function (src/bolt/ws.c)
  and the buffer_apply_mask function (src/bolt/buffer.c) in FalkorDB before
  4.20.0 allows a remote unauthenticated attacker to cause a denial of service
  and pos…
summary: >-
  A heap-based out-of-bounds write in the ws_read_frame function (src/bolt/ws.c)
  and the buffer_apply_mask function (src/bolt/buffer.c) in FalkorDB before
  4.20.0 allows a remote unauthenticated attacker to cause a denial of service
  and pos…
severity: critical
cvss: 9.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H'
cwe:
  - CWE-787
published: '2026-10-09'
updated: '2026-10-09'
sourceUpdated: '2026-10-09T06:17:12.413'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-107909'
references:
  - url: >-
      https://github.com/FalkorDB/FalkorDB/commit/0b11a00b34b25c4d4fdfe55f0a35c8a00593bd7d
    label: 33c584b5-0579-4c06-b2a0-8d8329fcab9c
  - url: 'https://github.com/FalkorDB/FalkorDB/pull/2170'
    label: 33c584b5-0579-4c06-b2a0-8d8329fcab9c
  - url: 'https://github.com/FalkorDB/FalkorDB/releases/tag/v4.20.0'
    label: 33c584b5-0579-4c06-b2a0-8d8329fcab9c
tags:
  - nvd
ingestedAt: '2026-10-09T06:27:05.589Z'
---

## Overview

A heap-based out-of-bounds write in the ws_read_frame function (src/bolt/ws.c) and the buffer_apply_mask function (src/bolt/buffer.c) in FalkorDB before 4.20.0 allows a remote unauthenticated attacker to cause a denial of service and possibly corrupt heap memory by sending a WebSocket frame with a 64-bit extended payload length to the Bolt port. The payload length is not bounded, and the only bounds check in buffer_apply_mask is an ASSERT(), which is compiled out in release builds, so the function XORs memory beyond the end of the receive buffer with the attacker-supplied mask key. Only deployments that enable the Bolt endpoint (BOLT_PORT, disabled by default) are affected.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.