CVE-2026-16558Public exploitNetwork attack vector

Stored XSS via unchecked layout schema rendering

Published Aug 8, 2026 · Updated Aug 8, 2026

Stored cross-site scripting in YMC Filter 3.6.0 through 3.12.7 allows remote authenticated users to execute JavaScript in visitors' browsers. The layout-saving REST handler accepts a post identifier and layout schema without verifying edit access to the selected post, while public filter rendering inserts the stored schema into the DOM without sanitizing or escaping it. Contributor access is sufficient, and execution occurs when a visitor views a filter that uses the attacker-controlled layout.

CVSS severity5.4
Medium
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored cross-site scripting in YMC Filter 3.6.0 through 3.12.7 allows remote authenticated users to execute JavaScript in visitors' browsers. The layout-saving REST handler accepts a post identifier and layout schema without verifying edit access to the selected post, while public filter rendering inserts the stored schema into the DOM without sanitizing or escaping it. Contributor access is sufficient, and execution occurs when a visitor views a filter that uses the attacker-controlled layout.

The record

CVE
CVE-2026-16558
Published
Aug 8, 2026
Updated
Aug 8, 2026
Vendor
YMC
Product
YMC Filter
Classifications
CWE-79, T1203
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 8, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 8, 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=3.6.0 <3.12.8

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

YMC · YMC Filterversion=3.6.0 <3.12.8

Published CVSS scores

5.4CISA-ADPCVSS:3.1/AV:N/AC:L/PR:L/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Cross-Site Scripting (XSS)
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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