PT-2026-28566 · Unknown · Handlebars

Byamb4 · Published 2026-03-26 · Updated 2026-05-18 · CVE-2026-33916

Positive Technologies (AI Summary)

CVSS v3.1

4.7

Medium

Base vector

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

Name of the Vulnerable Software and Affected Versions Handlebars versions 4.0.0 through 4.7.8

Description Handlebars is a templating engine that allows users to build semantic templates. Versions 4.0.0 through 4.7.8 contain a flaw in the resolvePartial() function within the Handlebars runtime. This function resolves partial names using a property lookup on options.partials without preventing prototype chain traversal. If Object.prototype is polluted with a string value matching a partial reference in a template, the polluted string is used as the partial body and rendered without HTML escaping, potentially leading to reflected or stored cross-site scripting (XSS).

Recommendations Update to version 4.7.9 or later. Apply Object.freeze(Object.prototype) early in application startup. Use the Handlebars runtime-only build (handlebars/runtime).

Exploit

Fix

Prototype Pollution

XSS

Weakness Enumeration

CWE-1321

CWE-79

Related Identifiers

CLEANSTART-2026-AD27625

CLEANSTART-2026-BE61221

CLEANSTART-2026-KS09647

CLEANSTART-2026-LC05413

CLEANSTART-2026-TW25027

CLEANSTART-2026-TZ34913

CVE-2026-33916

GHSA-2QVQ-RJWJ-GVW9

Affected Products

Handlebars

References · 262

• 🔥 https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33916.json · Exploit
• https://github.com/handlebars-lang/handlebars.js/commit/68d8df5a88e0a26fe9e6084c5c6aaebe67b07da2 · Patch
• https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-2qvq-rjwj-gvw9 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-39408 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2026-39406 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2026-33349 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2026-4926 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2026-29045 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2026-24842 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2026-33937 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2022-33987 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2026-42041 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2026-42036 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2026-4800 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2026-30827 · Security Note