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CVE-2026-93483

In Znuny through 7.3.6, an attacker can bypass specific standard login procedures and gain unauthorized access to sensitive system…

Critical9.5EPSS 0.23%
Published
Updated
Reserved
Assigned by
mitre

Description

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.

Timeline

  1. ID reserved

    By mitre

  2. · 27 days later

    Published

  3. · 4 days later

    Record updated

Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.

Scores

CVSS scores of CVE-2026-93483, by who scored it
Scored byCVSSScoreVector
mitreCNA (assigner)4.0Critical9.5CVSS: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
NVDNVD · Deferred4.0Critical9.5CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:L/SC:H/SI:H/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:Y/R:U/V:X/RE:L/U:Red
EPSS (exploitation in 30 days)
0.23% · top 86% of all CVEs (7 Nov 2026)
CISA SSVC
Exploitation: none · Automatable: no · Technical impact: total
Loading the EPSS history…

The list uses the assigner's score when there is one, then CISA's, then NVD's: Critical 9.5.

Weakness

Affected products

  • Znuny · Znuny

    • affected < 6.5.25
    • affected 7.0.0 – < 7.3.7

References (2)

Sources

The same CVE in the primary databases and aggregators, to check against.

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Record last updated .