---
id: CVE-2026-5720
title: >-
  miniupnpd contains an integer underflow vulnerability in SOAPAction header
  parsing that allows remote attackers to cause a denial of service or
  information disclosure by sending a malformed SOAPAction header with a single
  quote
summary: >-
  miniupnpd contains an integer underflow vulnerability in SOAPAction header
  parsing that allows remote attackers to cause a denial of service or
  information disclosure by sending a malformed SOAPAction header with a single
  quote. Attacker…
severity: critical
cvss: 9.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H'
cwe:
  - CWE-125
  - CWE-191
published: '2026-04-17'
updated: '2026-06-29'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-5720'
references:
  - url: 'https://github.com/miniupnp/miniupnp/'
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/miniupnp/miniupnp/commit/f56bd09b2f2650126b832c5f30a65a09e28167fa
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/miniupnpd-integer-underflow-soapaction-header-parsing
    label: disclosure@vulncheck.com
tags:
  - nvd
epss: 0.01071
epssPercentile: 0.63414
ingestedAt: '2026-06-29T14:29:18.063Z'
---

## Overview

miniupnpd contains an integer underflow vulnerability in SOAPAction header parsing that allows remote attackers to cause a denial of service or information disclosure by sending a malformed SOAPAction header with a single quote. Attackers can trigger an out-of-bounds memory read by exploiting improper length validation in ParseHttpHeaders(), where the parsed length underflows to a large unsigned value when passed to memchr(), causing the process to scan memory far beyond the allocated HTTP request buffer.

## Remediation

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