CVE-2023-6165VulnerabilityPublished 29 Jan 2024Updated 29 May 2025

CVE-2023-6165: Restrict Usernames Emails Characters (WordPress plugin) · Cross-Site Scripting (XSS)

Affects Restrict Usernames Emails Characters (WordPress plugin)Source CVE Database V5

Not known to be exploited · CVSS 4.8 Medium.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score

4.8Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.4% chance of exploitation in 30 days – higher than 34% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: High
User Interaction: Required
Scope: Changed
Confidentiality: Low
Integrity: Low
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: High: The attacker is authorized with (i.e., requires) privileges that provide significant (e.g., administrative) control over the vulnerable component that could affect component-wide settings and files.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 29 Jan 2024
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
Unknown Restrict Usernames Emails Characters	Affected =0	Fixed in–

AI-suggested

European organizations should immediately verify if their WordPress installations use the 'Restrict Usernames Emails Characters' plugin and identify the version in use. If the plugin version is prior to 3.1.4, they should upgrade to the latest version as soon as it becomes available. In the absence of an official patch, organizations can mitigate risk by restricting admin access strictly to trusted personnel, implementing strong multi-factor authentication (MFA) for all admin accounts, and auditing plugin settings for suspicious changes. Additionally, applying Web Application Firewall (WAF) rules to detect and block XSS payloads targeting plugin settings can reduce exploitation chances. Regular security reviews and monitoring of WordPress logs for unusual admin activity are recommended. Organizations should also consider disabling or replacing this plugin if it is not essential, to reduce the attack surface. Finally, educating administrators about the risks of injecting untrusted content into plugin settings can help prevent accidental exploitation.

Description

The Restrict Usernames Emails Characters WordPress plugin before 3.1.4 does not sanitise and escape some of its settings, which could allow high privilege users such as admin to perform Cross-Site Scripting attacks even when unfiltered_html is disallowed

Impact

For European organizations using WordPress sites with the 'Restrict Usernames Emails Characters' plugin, this vulnerability poses a risk primarily to site integrity and confidentiality. Since exploitation requires admin-level access, the threat is more relevant in scenarios where an attacker has already compromised or gained elevated privileges on the site. Successful exploitation could allow attackers to execute arbitrary JavaScript in the context of the admin user, potentially leading to session hijacking, privilege escalation, or further compromise of the WordPress environment. This could result in unauthorized access to sensitive data, defacement, or the planting of persistent backdoors. Given the widespread use of WordPress across European businesses, especially SMEs and content-driven organizations, the vulnerability could facilitate lateral movement or deeper compromise if combined with other attack vectors. However, the requirement for high privileges and user interaction limits the risk of widespread automated exploitation. The impact on availability is negligible, but confidentiality and integrity impacts are moderate, particularly for organizations handling sensitive user data or operating critical web services.

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #1OWASP Top 10 A05:2025: Injection (opens in a new tab)
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Implementation · Architecture and Design
Understand the context in which your data will be used and the encoding that will be expected. This is especially important when transmitting data between different components, or when generating outputs that can contain multiple encodings at the same time, such as web pages or multi-part mail messages.
Architecture and Design · Implementation · Attack Surface Reduction
Understand all the potential areas where untrusted inputs can enter your software: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide…
OWASP Cheat Sheets
Cross Site Scripting Prevention (opens in a new tab)
DOM based XSS Prevention (opens in a new tab)
Injection Prevention (opens in a new tab)
Abuse Case (opens in a new tab)
Deserialization (opens in a new tab)
OWASP ASVS 4.0.3
V5.3.3 (opens in a new tab)
V1.5.1 (opens in a new tab)
Attack patterns
XSS Using MIME Type Mismatch (opens in a new tab)
DOM-Based XSS (opens in a new tab)
Reflected XSS (opens in a new tab)
Stored XSS (opens in a new tab)
Cross-Site Scripting (XSS) (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 8 Jul 2025, 01:12 UTC

WeaknessesCWE-79

Technical details

References

Community reviews

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