CVE-2026-16559Public exploitNetwork attack vector

Author-level stored XSS via SVG sanitizer bypass

Published Aug 8, 2026 · Updated Aug 8, 2026

Stored XSS in YMC Filter before 3.12.9 allows remote authenticated users with Author access to execute JavaScript via an uploaded SVG. The term-icon REST upload applies byte-oriented, single-pass regex stripping, allowing nested tags or UTF-16 encoding to evade sanitization. Author access and a victim opening the stored SVG are required; the script then runs in the WordPress site's origin.

CVSS severity6.8
Medium
EPSS probability0.23%
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 YMC Filter before 3.12.9 allows remote authenticated users with Author access to execute JavaScript via an uploaded SVG. The term-icon REST upload applies byte-oriented, single-pass regex stripping, allowing nested tags or UTF-16 encoding to evade sanitization. Author access and a victim opening the stored SVG are required; the script then runs in the WordPress site's origin.

The record

CVE
CVE-2026-16559
Published
Aug 8, 2026
Updated
Aug 8, 2026
Vendor
YMC
Product
YMC Filter
Classifications
CWE-79, CAPEC-592, 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=0 <3.12.9

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

YMC · YMC Filterversion=0 <3.12.9

Published CVSS scores

6.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:H

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-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CAPEC-592Stored 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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