Znuny up to 6.5.24/7.3.6 HTTPBasicAuth HTTP_REMOTE_USER improper authentication

Summaryinfo

A vulnerability was found in Znuny up to 6.5.24/7.3.6 and classified as critical. This affects the function Kernel::System::Auth::HTTPBasicAuth/Kernel::System::CustomerAuth::HTTPBasicAuth of the component HTTPBasicAuth. Executing a manipulation of the argument HTTP_REMOTE_USER can lead to improper authentication. This vulnerability is handled as CVE-2026-93483. The attack can be executed remotely. There is not any exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability has been found in Znuny up to 6.5.24/7.3.6 and classified as critical. This vulnerability affects the function Kernel::System::Auth::HTTPBasicAuth/Kernel::System::CustomerAuth::HTTPBasicAuth of the component HTTPBasicAuth. The manipulation of the argument HTTP_REMOTE_USER with an unknown input leads to a improper authentication vulnerability. The CWE definition for the vulnerability is CWE-287. When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is available at znuny.org. This vulnerability was named CVE-2026-93483 since 09/18/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Technical details are known, but there is no available exploit.

Upgrading to version 6.5.25 or 7.3.7 eliminates this vulnerability.

If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Name

• Znuny

Version

• 6.5.0
• 6.5.1
• 6.5.2
• 6.5.3
• 6.5.4
• 6.5.5
• 6.5.6
• 6.5.7
• 6.5.8
• 6.5.9
• 6.5.10
• 6.5.11
• 6.5.12
• 6.5.13
• 6.5.14
• 6.5.15
• 6.5.16
• 6.5.17
• 6.5.18
• 6.5.19
• 6.5.20
• 6.5.21
• 6.5.22
• 6.5.23
• 6.5.24
• 7.3.0
• 7.3.1
• 7.3.2
• 7.3.3
• 7.3.4
• 7.3.5
• 7.3.6

CPE 2.3info

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CPE 2.2info

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