PT-2026-60078 · Packagist · Nukeviet/Nukeviet

CVE-2026-49259

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Published

2026-07-13

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Updated

2026-07-13

CVSS v3.1

8.7

High

VectorAV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N

Summary

A stored cross-site scripting (XSS) vulnerability exists in NukeViet CMS versions 4.x through 4.5.08. A low-privileged authenticated user can store a JavaScript payload in their profile's display name fields. The payload executes in the browser of any visitor — including administrators — who clicks the Reply ("Answer") link on a comment posted by that user.

Affected Component

The {COMMENT.post name} template variable is interpolated without JavaScript-context escaping into an inline onclick handler in both comment block positions:
  • themes/default/modules/comment/comment.tpl line 27 (top-level comments)
  • themes/default/modules/comment/comment.tpl line 64 (nested/reply comments)
html
onclick="nv commment feedback(event, {COMMENT.cid}, '{COMMENT.post name}')"

Root Cause

The first name and last name profile fields are sanitized with HTML numeric character references (' → ', ( → (, ) → ), / → /) via Request:: get title() with $specialchars = true. This encoding is correct for plain HTML attribute and element contexts, but insufficient for a JavaScript string literal embedded inside an HTML attribute.
Browsers decode HTML entities in attribute values before the JavaScript engine parses the string. As a result, ' is decoded back to ', which terminates the JS string early and allows the remainder of the value to be executed as JavaScript.
The combined display name (nv show name user(first name, last name)) is what reaches the template, giving an attacker up to ~200 encoded characters across both fields — sufficient for any practical payload.

Proof of Concept

Set first name to the following value in profile settings (/index.php?nv=users&op=editinfo), then post any comment:
text
a');alert(document.domain);//
The value is stored as a');alert(document.domain);//.
When a visitor clicks the Reply link on the comment, the browser renders:
js
nv commment feedback(event, 1, 'a');alert(document.domain);// Tester')
causing alert(document.domain) to execute in the visitor's browser context.
A data-exfiltration variant (split across both name fields) navigates the victim's browser to an attacker-controlled URL carrying document.cookie as a query parameter. End-to-end verification was performed using a local listener.

Exploitation Conditions (default configuration)

ConditionDefault valueEffect
captcha area comm1No CAPTCHA for logged-in users — payload delivery requires no CAPTCHA solve
auto postcommenabledComments are published immediately without moderation
active editinfo censor0Profile edits take effect immediately without admin review
CSP script-src'unsafe-inline'Inline onclick handlers execute normally
Any registered member can set the payload and post a comment with no additional steps.
If captcha area comm is set to 0, the name field of anonymous comments (modules/comment/funcs/post.php) is processed by the same get title(..., 1) call, making exploitation possible without authentication.

Impact

An attacker with a regular user account can execute arbitrary JavaScript in the browser of any visitor who interacts with the Reply button on their comment, including site administrators.
Practical consequences include:
  • Privilege escalation via admin session hijacking — forging administrative actions (content modification, account manipulation) in the context of an authenticated admin.
  • Credential phishing — injecting a fake login form into the page.
  • Data exfiltration — reading page content and non-HttpOnly cookies.
Note: NukeViet session cookies carry the HttpOnly flag, so they are not directly readable via document.cookie; however, the above attack vectors remain fully viable.

Remediation

Preferred fix: Remove post name from the inline handler entirely. Pass only cid to nv commment feedback and have the function retrieve the display name from the already-rendered DOM (e.g., the adjacent <strong class="cm item"> element).
Alternative fix: If the value must be passed inline, encode it with json encode($post name) (PHP) so that the output is a properly escaped JavaScript string literal, not an HTML-entity-encoded one. HTML numeric character references must not be relied upon for JavaScript string escaping.
As a general note, the result of get title(..., $specialchars=true) is safe for HTML element content and quoted HTML attribute values, but unsafe when placed inside a JavaScript string literal within an attribute. Other locations in the codebase using the same pattern should be audited.

Resources

  • OWASP: Cross Site Scripting Prevention — Rule 2: Attribute Encoding is Not Sufficient for JS Contexts
  • CWE-79: Improper Neutralization of Input During Web Page Generation
  • CWE-116: Improper Encoding or Escaping of Output

Fix

XSS

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Weakness Enumeration

CWE-79

Related Identifiers

CVE-2026-49259
GHSA-W2W5-W2PW-R929

Affected Products

Nukeviet/Nukeviet