Unauthenticated impersonation via trusted HTTP header
Published Oct 15, 2026 · Updated Oct 15, 2026
Authentication bypass in Znuny 7.3.6 and earlier allows remote attackers to impersonate existing users via a forged HTTP header. The agent and customer HTTPBasicAuth modules fall back from the web-server-authenticated REMOTE_USER environment variable to HTTP_REMOTE_USER, which accepts the attacker-controlled Remote-User header. Exploitation requires HTTPBasicAuth as the authentication backend and grants the impersonated account's access to confidential data and system controls, including administrator access.
Summary
What happened
Authentication bypass in Znuny 7.3.6 and earlier allows remote attackers to impersonate existing users via a forged HTTP header. The agent and customer HTTPBasicAuth modules fall back from the web-server-authenticated REMOTE_USER environment variable to HTTP_REMOTE_USER, which accepts the attacker-controlled Remote-User header. Exploitation requires HTTPBasicAuth as the authentication backend and grants the impersonated account's access to confidential data and system controls, including administrator access.
The record
- CVE
- CVE-2026-93483
- Published
- Oct 15, 2026
- Updated
- Oct 15, 2026
- Vendor
- Znuny GmbH
- Product
- Znuny
- Classifications
- CWE-348, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Oct 15, 2026CVE publishedPublication date reported by the CVE source.
- Oct 15, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <6.5.25
- Affected versionversion=7.0.0 <7.3.7
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Activity data is delayed. The latest report is Sep 28, 2026.
Public exploit references
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Technologies
Your stack
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