---
id: "CVE-2026-115457"
kind: "vulnerability"
aliases: ["CVE-2026-115457"]
title: "baserCMS: blog comment shortcodes enable stored cross-site scripting"
severity: "high"
cvss: 7.1
epss: 0.0041
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["basercms", "blog-comments", "package", "php", "self-hosted"]
not_affected_if: ["comments-disabled", "patched-version"]
published_at: "2026-10-23T14:17:51+00:00"
first_seen_at: "2026-10-23T21:57:34+00:00"
updated_at: "2026-10-25T12:38:50+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-115457", "first_seen_at": "2026-10-23T21:57:34+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-115457", "first_seen_at": "2026-10-25T12:38:50+00:00"}]
---

# baserCMS: blog comment shortcodes enable stored cross-site scripting

baserCMS expands shortcodes across the whole rendered page, including blog comments posted by anonymous visitors, so a comment containing a BcBaser.getGoogleMaps shortcode can load an attacker-controlled script. The script runs on the site's origin when another visitor or an administrator opens the article, and can act in the administrator's logged-in browser session.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the baserCMS version with `composer show basercms/basercms` or the admin footer; affected versions are 5.0.0 to before 5.3.2 and 5.4.0 to before 5.4.2.
- Search stored blog comments for the string `BcBaser.getGoogleMaps` (unknown whether the sources give a database query).

## Fix

- Upgrade baserCMS to `5.3.2` on the 5.3 line or `5.4.2` on the 5.4 line.
- Review existing blog comments for shortcode text and remove any that reference unexpected script URLs.

## Timeline

- 2026-10-23T21:57:34+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-115457
- 2026-10-25T12:38:50+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-115457

## From the sources

baserCMS is a website development framework. In versions 5.0.0 before 5.3.2 and 5.4.0 before 5.4.2, global shortcode expansion runs over the complete rendered page, including HTML-escaped blog comments supplied by unauthenticated visitors. A comment containing the BcBaser.getGoogleMaps shortcode can set apiBaseUrl to an attacker-controlled script URL, which is emitted as a script src and executes JavaScript on the site's origin when another visitor or administrator opens the article displaying that comment. Escaping raw HTML in comments does not prevent this stored cross-site scripting because shortcode processing happens after HTML rendering. Other registered shortcodes also expand in comments; Mail.getForm can embed a working contact form with a valid CSRF token. The flaw can compromise the authenticated browser context of an administrator who views the affected article. This issue has been patched in versions 5.3.2 and 5.4.2.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_