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Page Builder CK EUVDEUVD-2026-64751

| CVE-2026-77993 MEDIUM
Cross-site Scripting (XSS) (CWE-79)
2026-08-24 security@joomla.org GHSA-vrrp-8526-8v58
5.3
CVSS 4.0 · Vendor: joomla
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Severity by source

Vendor (joomla) PRIMARY
5.3 MEDIUM
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/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:X/R:X/V:X/RE:X/U:X
vuln.today AI
6.1 MEDIUM

Network-accessible reflected XSS with no privileges, requiring victim click (UI:R); scope changes to victim's browser context (S:C) with low C/I and no availability impact.

3.1 AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
4.0 AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (joomla).

CVSS VectorVendor: joomla

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/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:X/R:X/V:X/RE:X/U:X
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
P
Scope
X

Lifecycle Timeline

1
Analysis Generated
Aug 24, 2026 - 08:31 vuln.today

DescriptionCVE.org

Joomla Extension - joomlack.fr - Reflected XSS in Page Builder CK < 3.6.5 - The Joomla extension Page Builder CK is vulnerable to a reflected XSS via the iscontenttype parameter.

AnalysisAI

Reflected XSS in Page Builder CK, a third-party Joomla extension by joomlack.fr, allows unauthenticated remote attackers to inject and execute arbitrary JavaScript in a victim's browser by crafting a malicious URL that embeds a payload in the iscontenttype parameter. All versions prior to 3.6.5 are affected; exploitation requires passive user interaction - a victim must click or be redirected to the crafted URL. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Recon
Identify Joomla site running Page Builder CK < 3.6.5
Delivery
Craft URL with XSS payload in `iscontenttype` parameter
Exploit
Deliver crafted URL to victim via phishing or redirect
Install
Victim clicks URL, browser sends request to extension
C2
Server reflects unescaped parameter into HTML response
Execute
JavaScript executes in victim's browser session
Impact
Exfiltrate session token or perform authenticated actions

Vulnerability AssessmentAI

Exploitation The target environment must be running the Joomla CMS with the Page Builder CK extension installed and active in a version prior to 3.6.5. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment The CVSS 4.0 score of 5.3 reflects moderate severity with a vector of AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:L, indicating network-reachable, low-complexity exploitation with no privileges required but passive user interaction needed. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario An attacker identifies a Joomla site running Page Builder CK below 3.6.5 and crafts a URL with a JavaScript payload embedded in the `iscontenttype` parameter. The attacker delivers the URL via a phishing email targeting a Joomla editor or administrator; when the victim clicks the link, the extension reflects the unescaped payload directly into the page HTML, executing the script in the victim's authenticated browser session and potentially exfiltrating session cookies to an attacker-controlled server. …
Remediation Upgrade Page Builder CK to version 3.6.5 or later, which resolves the reflected XSS by properly encoding the `iscontenttype` parameter before rendering. … Detailed patch versions, workarounds, and compensating controls in full report.

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EUVD-2026-64751 vulnerability details – vuln.today

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