CVE-2026-77506Network attack vector

Cross-site scripting via missing output filters

Published Aug 20, 2026 · Updated Aug 20, 2026

Cross-site scripting in AgentTicketEmailResend in Znuny before LTS 6.5.22 allows remote authenticated users to run script in another agent's browser. The AgentTicketEmailResend template renders user-controlled resend data without the HTML output filters that Znuny identifies as required, so attacker-supplied HTML or JavaScript is emitted into the page. Exploitation requires agent-interface access and a way to make another agent open the resend view; the documented consequence is browser-session code execution in that user's context rather than server-side execution.

CVSS severity4.8
Medium
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in AgentTicketEmailResend in Znuny before LTS 6.5.22 allows remote authenticated users to run script in another agent's browser. The AgentTicketEmailResend template renders user-controlled resend data without the HTML output filters that Znuny identifies as required, so attacker-supplied HTML or JavaScript is emitted into the page. Exploitation requires agent-interface access and a way to make another agent open the resend view; the documented consequence is browser-session code execution in that user's context rather than server-side execution.

The record

CVE
CVE-2026-77506
Published
Aug 20, 2026
Updated
Aug 20, 2026
Vendor
Znuny GmbH
Product
Znuny
Classifications
T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 20, 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.

  1. Affected versionversion=6.0 <6.5.22

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Znuny GmbH · Znunyversion=6.0 <6.5.22

Published CVSS scores

4.8TenableCVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N

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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1059.007Command and Scripting Interpreter: JavaScript

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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