CVE-2026-8873Network attack vector

Stored XSS via unescaped shortcode attributes

Published May 27, 2026 · Updated May 27, 2026

Stored XSS in Cello Expressions Content Slideshow 2.4.1 and earlier allows remote authenticated users to inject scripts via shortcode attributes. The shortcode handler in slideshow-widget-shortcode.php accepts user-controlled attributes and renders them without sufficient sanitization or output escaping. Contributor-level access is required to store the payload, which runs in a visitor's browser when the affected page is viewed.

CVSS severity6.4
Medium
EPSS probability0.19%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in Cello Expressions Content Slideshow 2.4.1 and earlier allows remote authenticated users to inject scripts via shortcode attributes. The shortcode handler in slideshow-widget-shortcode.php accepts user-controlled attributes and renders them without sufficient sanitization or output escaping. Contributor-level access is required to store the payload, which runs in a visitor's browser when the affected page is viewed.

The record

CVE
CVE-2026-8873
Published
May 27, 2026
Updated
May 27, 2026
Vendor
Cello Expressions
Product
Content Slideshow
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 27, 2026CVE publishedPublication date reported by the CVE source.
  2. May 27, 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=0 <=2.4.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Cello Expressions · Content Slideshowversion=0 <=2.4.1

Published CVSS scores

6.4WordfenceCVSS:3.1/AV:N/AC:L/PR:L/UI:N/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007JavaScript/JScript

Public exploit references

No public exploit references are available in this record.

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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