---
id: CVE-2026-85440
title: >-
  MOOS core-moos through 10.4.0 contains a pre-authentication heap overflow
  vulnerability in MOOSCommPkt packet handling that allows remote attackers to
  write arbitrary data by declaring a negative packet length
summary: >-
  MOOS core-moos through 10.4.0 contains a pre-authentication heap overflow
  vulnerability in MOOSCommPkt packet handling that allows remote attackers to
  write arbitrary data by declaring a negative packet length. Attackers can
  exploit the …
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-787
published: '2026-09-03'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T20:07:17.943'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-85440'
references:
  - url: 'https://github.com/themoos/core-moos'
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/themoos/core-moos/blob/ec9c77c68fcbdef8f5e4c60fe243acd223433f0c/Core/libMOOS/Comms/MOOSCommPkt.cpp#L67
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/themoos/core-moos/commit/96c49c5cdda6e07ee734a5324e8d25ba5a7f2d7a
    label: disclosure@vulncheck.com
  - url: 'https://github.com/themoos/core-moos/pull/82'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/moos-core-moos-through-10.4.0-moosdb-pre-authentication-heap-overflow-via-negative-packet-length
    label: disclosure@vulncheck.com
tags:
  - nvd
epss: 0.0103
epssPercentile: 0.62218
ingestedAt: '2026-09-08T20:10:03.161Z'
---

## Overview

MOOS core-moos through 10.4.0 contains a pre-authentication heap overflow vulnerability in MOOSCommPkt packet handling that allows remote attackers to write arbitrary data by declaring a negative packet length. Attackers can exploit the signed integer check in InflateTo() and negative size conversion in recv() to overflow a four-byte heap buffer during the HandShake phase before authentication.

## Remediation

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