CVE-2026-40565Public exploitNetwork attack vector

Stored CSS injection via unescaped linkified URL

Published Apr 21, 2026 · Updated Apr 21, 2026

Stored CSS injection in FreeScout before 1.8.213 allows remote attackers to alter an agent's interface via a crafted URL in an email. Helper::linkify() accepts double quotes in its URL match and inserts the match unescaped into an href attribute rendered as raw HTML. An agent must view the conversation; the default CSP permits a full-page style overlay but blocks injected event-handler script.

CVSS severity6.1
Medium
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored CSS injection in FreeScout before 1.8.213 allows remote attackers to alter an agent's interface via a crafted URL in an email. Helper::linkify() accepts double quotes in its URL match and inserts the match unescaped into an href attribute rendered as raw HTML. An agent must view the conversation; the default CSP permits a full-page style overlay but blocks injected event-handler script.

The record

CVE
CVE-2026-40565
Published
Apr 21, 2026
Updated
Apr 21, 2026
Vendor
FreeScout
Product
FreeScout
Classifications
CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 21, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 21, 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=< 1.8.213

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

FreeScout · FreeScoutversion=< 1.8.213

Published CVSS scores

6.1GitHubCVSS:3.1/AV:N/AC:L/PR:N/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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