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mediumCross-site Scriptingpublic exploit

CVE-2026-18547

CVE-2026-18547 — Ultimate Member <= 2.12.1 - Authenticated (Subscriber+) Stored Cross-Site Scripting via Textarea Profile Field with HTML Support (DOM Gadget via id Attribute)

The Ultimate Member – User Profile, Registration, Login, Member Directory, Content Restriction & Membership Plugin plugin for WordPress is vulnerable to Stored Cross-Site Scripting via Textarea Profile Field with HTML Support (DOM Gadget via id Attribute) in all versions up to, and including, 2.12.1 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with subscriber-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This is possible because the wp_kses 'templates' allowlist permits the id attribute on div elements but does not neutralize unescaped quotes within its value; when pickadate.js concatenates the stored id value into an HTML string via jQuery .html() on profile page load, the smuggled onfocus and autofocus attribute syntax breaks out of attribute context and executes as JavaScript.

Published Updated Sources: NVD, ultimatemember (CNA), GitHub, GitHub Security Advisory, SOCRadar CTI

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.

Exploitation

Reported

not confirmed by CISA

EPSS

0%

ahead of 0% of scored CVEs

Affects

ultimatemember

Ultimate Member – User Profile, Registration, Login, Member Directory, Content Restriction & Membership Plugin

CVSS base

6.4

medium

Remediation

The vendor's own words where we have them.

Upgrade Ultimate Member – User Profile, Registration, Login, Member Directory, Content Restriction & Membership Plugin to a fixed release. Apply vendor patches per advisory and restrict external exposure of the affected component until patched.

First 24 hours

Ordered from the record's own fields — exposure first, because you cannot patch what you have not found.

  • Identify exposed assets running affected vendor/product/version combinations.
  • Prioritize based on EPSS, PoC availability, and external exposure.
  • Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class.

Affected scope

Vendor, product and version as the advisories word them.

VendorProductVersionsStatus
ultimatememberUltimate Member – User Profile, Registration, Login, Member Directory, Content Restriction & Membership Plugin0 to <= 2.12.1Vulnerable

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Availability

None

Confidentiality

Low

Integrity

Low

Scope

Changed

Attack Complexity

Low

Attack Vector

Network

Privileges Req

Low

User Interaction

None

Every base score collected

Sources score independently and disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactSource
6.4CVSS 3.1medium3.12.7NVD, ultimatemember (CNA), GHSA

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

What this weakness leads to

MITRE's own consequences and mitigations for the weakness class — the authority's wording, not guidance derived from the CVSS vector.

MITRE

CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

  • Bypass Protection Mechanism
  • Read Application Data
  • Execute Unauthorized Code or Commands

Mitigation: Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples of libraries and frameworks that make it easier to generate properly encoded output include Microsoft's Anti-XSS library, the OWASP ESAPI Encoding module, and Apache Wicket.

Weakness & attack patterns

  • CWE-79Cross-site Scripting

Attack patterns reported against this CVE. The ATT&CK techniques below are inferred from its weakness class.

CAPEC-85 · AJAX FingerprintingCAPEC-592 · Stored XSSCAPEC-591 · Reflected XSSCAPEC-63 · Cross-Site Scripting (XSS)CAPEC-588 · DOM-Based XSSCAPEC-209 · XSS Using MIME Type Mismatch

Public exploit

Capability, not use: code existing is a different claim from anyone running it.

Repositories

3

1 of the 3 sampled are weaponized

Detection

Read off the CVSS vector and the weakness class. Starting points, not rules we have tested.

  • Prioritize edge telemetry for network-reachable Ultimate Member – User Profile, Registration, Login, Member Directory, Content Restriction & Membership Plugin.
  • Monitor for scanner or exploit-pattern traffic after 3 public PoC repositories were reported.
web/proxy/WAF logsapplication logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first — with the readings a source repeats on a schedule counted underneath rather than listed.

  1. 2026

  2. Added · CVSS 3.1 6.4 (AV:N)

    Aug 25, 2026 · NVD

  3. Initial · CVE published

    Aug 25, 2026 · NVD

  4. Added · GHSA-rhh6-vxq9-rqm4 published (medium)

    Aug 25, 2026 · GitHub Security Advisory

  5. Reported · Disclosed

    Aug 24, 2026 · ultimatemember

  6. Reported · Vendor Notified

    Jul 31, 2026 · ultimatemember

Source activity

Readings a source repeats on a schedule, counted rather than listed.

  • 1×CVE modified by NIST, Modified, LinkAug 25, 2026 · SOCRadar CTI

References

10 on the record

Elsewhere on this site

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record1

What should defenders know first?

CVE-2026-18547 is Ultimate Member <= 2.12.1 - Authenticated (Subscriber+) Stored Cross-Site Scripting via Textarea Profile Field with HTML Support (DOM Gadget via id Attribute), a medium vulnerability affecting Ultimate Member – User Profile, Registration, Login, Member Directory, Content Restriction & Membership Plugin from ultimatemember. The current evidence does not list it in CISA KEV, and the exploit status is: Exploitation is reported, but no independent confirmation is available in the sources we have. Public exploit evidence is: 3 public PoC repositories reported; 1 marked weaponized in current dataset. The affected-version evidence is listed in the key facts and affected products tables. Defenders should first verify whether exposed or business-critical assets run those versions, then apply vendor patches or mitigations, restrict reachable attack surface, and preserve logs for detection review. CVSS 6.4 describes technical severity, while EPSS 0% helps estimate near-term exploit likelihood; neither replaces asset context. Unknown fields should remain explicit in tickets, and threat actor, IOC, victimology, or payload claims should not be added unless a cited source supports them. Monitor CISA KEV, vendor advisories, NVD changes, public PoC repositories, and internal telemetry for update triggers.