---
id: CVE-2026-93483
title: >-
  In Znuny through 7.3.6, an attacker can bypass specific standard login
  procedures and gain unauthorized access to sensitive system functions by
  manipulating a specific HTTP request header
summary: >-
  In Znuny through 7.3.6, an attacker can bypass specific standard login
  procedures and gain unauthorized access to sensitive system functions by
  manipulating a specific HTTP request header. Because the application
  incorrectly trusts this …
severity: critical
cwe:
  - CWE-348
published: '2026-10-15'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T04:18:30.153'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-93483'
references:
  - url: 'https://www.znuny.org/advisories'
    label: cve@mitre.org
  - url: 'https://www.znuny.org/en/advisories/zsa-2026-14'
    label: cve@mitre.org
tags:
  - nvd
  - cve.org
ingestedAt: '2026-10-15T04:46:37.142Z'
vendor: Znuny
product: Znuny
affected:
  - Znuny < 6.5.25
  - Znuny >= 7.0.0 < 7.3.7
cvss: 9.5
cvssVector: >-
  CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:L/SC:H/SI:H/SA:L/AU:Y/R:U/RE:L/U:Red
cvssSource: cna
---

## Overview

In Znuny through 7.3.6, an attacker can bypass specific standard login procedures and gain unauthorized access to sensitive system functions by manipulating a specific HTTP request header. Because the application incorrectly trusts this header, an attacker can impersonate any user, including administrators, without requiring a password. This grants full access to confidential data and system controls. More specifically, the HTTPBasicAuth modules for the agent (Kernel::System::Auth::HTTPBasicAuth) and customer (Kernel::System::CustomerAuth::HTTPBasicAuth) interfaces read the username to log in not only from $ENV{REMOTE_USER} (set by the web server after successful authentication), but also, as a fallback, from $ENV{HTTP_REMOTE_USER}, which is populated directly from an attacker-controllable "Remote-User" request header. On systems where HTTPBasicAuth was configured as the authentication backend, this allowed an attacker to log in as any existing user by sending a request with a forged Remote-User header, without providing any credentials.

## Remediation

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