PT-2026-33174 · Npm+1 · Sanitize-Html+1

Published 2026-04-15 · Updated 2026-04-16 · CVE-2026-40186

Positive Technologies (AI Summary)

CVSS v3.1

6.1

Medium

Base vector

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

Name of the Vulnerable Software and Affected Versions ApostropheCMS versions prior to 4.29.0 sanitize-html version 2.17.1

Description A regression in the sanitize-html package allows a bypass of allowedTags enforcement for text within nonTextTagsArray elements, specifically textarea and option. The code in 'packages/sanitize-html/index.js' incorrectly assumes that htmlparser2 does not decode entities inside these elements and skips escaping. However, htmlparser2 10.x decodes entities before passing text to the ontext callback, causing entity-encoded HTML to be written directly to the output as literal HTML characters. This enables an attacker to inject arbitrary tags, including cross-site scripting (XSS) payloads, through any allowed option or textarea element using entity encoding. This occurs in non-default configurations where these elements are included in allowedTags.

Recommendations Update ApostropheCMS to version 4.29.0. Update sanitize-html to version 2.17.2.

Fix

XSS

Weakness Enumeration

CWE-79

Related Identifiers

CVE-2026-40186

GHSA-9MRH-V2V3-XPFM

Affected Products

Apostrophe Cms

Sanitize-Html

References · 7

• https://github.com/apostrophecms/apostrophe/security/advisories/GHSA-9mrh-v2v3-xpfm · Vendor Advisory
• https://github.com/apostrophecms/apostrophe/commit/7ca2d16237c72718ef7e5c7ae0458e6027ac4f64 · Patch
• https://nvd.nist.gov/vuln/detail/CVE-2026-40186 · Security Note
• https://osv.dev/vulnerability/GHSA-9mrh-v2v3-xpfm · Vendor Advisory
• https://github.com/apostrophecms/apostrophe · Note
• https://twitter.com/CVEnew/status/2044701618080481631 · Twitter Post
• https://twitter.com/VulmonFeeds/status/2044541164309668256 · Twitter Post