CVE-2026-65903

Versions of handlebars prior to 3.0.8 or 4.5.3 are vulnerable to Arbitrary Code Execution. The package's lookup helper fails to properly validate templates, allowing attackers to submit templates that execute arbitrary JavaScript in the system. It is due to an incomplete fix for a previous issue. This vulnerability can be used to run arbitrary code in a server processing Handlebars templates or on a victim's browser (effectively serving as Cross-Site Scripting).

Recommendation

Upgrade to version 3.0.8, 4.5.3 or later.

DOMPurify before 3.4.0 contains a logic error in the ADD_TAGS function where short-circuit evaluation allows forbidden tags to bypass FORBID_TAGS restrictions. Attackers can craft input containing tags listed in FORBID_TAGS that are also added via ADD_TAGS function, causing them to be retained in sanitized output.

DOMPurify before 3.4.0 contains a logic error in the ADD_TAGS function where short-circuit evaluation allows forbidden tags to bypass FORBID_TAGS restrictions. Attackers can craft input containing tags listed in FORBID_TAGS that are also added via ADD_TAGS function, causing them to be retained in sanitized output.

DOMPurify before 3.4.0 contains a logic error in the ADD_TAGS function where short-circuit evaluation allows forbidden tags to bypass FORBID_TAGS restrictions. Attackers can craft input containing tags listed in FORBID_TAGS that are also added via ADD_TAGS function, causing them to be retained in sanitized output.

Versions of handlebars prior to 3.0.8 or 4.5.2 are vulnerable to Arbitrary Code Execution. The package's lookup helper fails to properly validate templates, allowing attackers to submit templates that execute arbitrary JavaScript in the system. It can be used to run arbitrary code in a server processing Handlebars templates or on a victim's browser (effectively serving as Cross-Site Scripting).

The following template can be used to demonstrate the vulnerability:

	{{#with split as |a|}}
		{{pop (push "alert('Vulnerable Handlebars JS');")}}
		{{#with (concat (lookup join (slice 0 1)))}}
			{{#each (slice 2 3)}}
				{{#with (apply 0 a)}}
					{{.}}
				{{/with}}
			{{/each}}
		{{/with}}
	{{/with}}
{{/with}}```


## Recommendation

Upgrade to version 3.0.8, 4.5.2 or later.

Summary

In src/purify.ts:1117-1123, ADD_TAGS as a function (via EXTRA_ELEMENT_HANDLING.tagCheck) bypasses FORBID_TAGS due to short-circuit evaluation.

The condition:

!(tagCheck(tagName)) && (!ALLOWED_TAGS[tagName] || FORBID_TAGS[tagName])

When tagCheck(tagName) returns true, the entire condition is false and the element is kept — FORBID_TAGS[tagName] is never evaluated.

Inconsistency

This contradicts the attribute-side pattern at line 1214 where FORBID_ATTR explicitly wins first:

if (FORBID_ATTR[lcName]) { continue; }

For tags, FORBID should also take precedence over ADD.

Impact

Applications using both ADD_TAGS as a function and FORBID_TAGS simultaneously get unexpected behavior — forbidden tags are allowed through. Config-dependent but a genuine logic inconsistency.

Suggested Fix

Check FORBID_TAGS before tagCheck:

if (FORBID_TAGS[tagName]) { /* remove */ }
else if (tagCheck(tagName) || ALLOWED_TAGS[tagName]) { /* keep */ }

Affected Version

v3.3.3 (commit 883ac15)

Versions of handlebars prior to 4.0.14 are vulnerable to Prototype Pollution. Templates may alter an Objects' prototype, thus allowing an attacker to execute arbitrary code on the server.

Recommendation

For handlebars 4.1.x upgrade to 4.1.2 or later. For handlebars 4.0.x upgrade to 4.0.14 or later.

DOMPurify before 3.4.0 contains a logic error in the ADD_TAGS function where short-circuit evaluation allows forbidden tags to bypass FORBID_TAGS restrictions. Attackers can craft input containing tags listed in FORBID_TAGS that are also added via ADD_TAGS function, causing them to be retained in sanitized output.

TuxCare rebuilt handlebars to address 1 CVE. Fixed in 1.3.0-tuxcare.1.

TuxCare rebuilt handlebars to address 3 CVEs. Fixed in 1.0.12-tuxcare.2.

TuxCare rebuilt dompurify to address 6 CVEs. Fixed in 3.1.6-tuxcare.3.

TuxCare rebuilt dompurify to address 10 CVEs. Fixed in 3.2.3-tuxcare.1.

TuxCare rebuilt dompurify to address 10 CVEs. Fixed in 3.0.3-tuxcare.1.

TuxCare rebuilt dompurify to address 9 CVEs. Fixed in 2.4.0-tuxcare.1.

TuxCare rebuilt dompurify to address 9 CVEs. Fixed in 2.4.7-tuxcare.1.

TuxCare rebuilt dompurify to address 5 CVEs. Fixed in 2.5.8-tuxcare.4.

TuxCare rebuilt dompurify to address 1 CVE. Fixed in 2.4.3-tuxcare.3.

TuxCare rebuilt dompurify to address 1 CVE. Fixed in 2.3.0-tuxcare.2.

TuxCare rebuilt dompurify to address 16 CVEs. Fixed in 2.4.0-tuxcare.1.

TuxCare rebuilt dompurify to address 14 CVEs. Fixed in 2.4.7-tuxcare.1.

TuxCare rebuilt dompurify to address 34 CVEs. Fixed in 3.0.3-tuxcare.1.

TuxCare rebuilt dompurify to address 5 CVEs. Fixed in 3.3.3-tuxcare.2.

TuxCare rebuilt dompurify to address 10 CVEs. Fixed in 2.0.8-tuxcare.3.

TuxCare rebuilt dompurify to address 12 CVEs. Fixed in 2.3.3-tuxcare.3.

TuxCare rebuilt dompurify to address 9 CVEs. Fixed in 3.2.6-tuxcare.3.

TuxCare rebuilt dompurify to address 13 CVEs. Fixed in 2.3.10-tuxcare.3.

TuxCare rebuilt dompurify to address 10 CVEs. Fixed in 3.0.1-tuxcare.3.

TuxCare rebuilt dompurify to address 10 CVEs. Fixed in 3.0.2-tuxcare.3.

TuxCare rebuilt dompurify to address 8 CVEs. Fixed in 3.0.8-tuxcare.3.

TuxCare rebuilt dompurify to address 9 CVEs. Fixed in 3.0.9-tuxcare.3.

TuxCare rebuilt dompurify to address 7 CVEs. Fixed in 3.0.11-tuxcare.3.

TuxCare rebuilt dompurify to address 6 CVEs. Fixed in 3.1.0-tuxcare.3.

TuxCare rebuilt dompurify to address 8 CVEs. Fixed in 3.1.3-tuxcare.3.

TuxCare rebuilt dompurify to address 10 CVEs. Fixed in 3.1.2-tuxcare.3.

TuxCare rebuilt dompurify to address 11 CVEs. Fixed in 3.1.1-tuxcare.3.

TuxCare rebuilt dompurify to address 8 CVEs. Fixed in 3.1.4-tuxcare.3.

Versions of handlebars prior to 3.0.8 or 4.5.3 are vulnerable to prototype pollution. It is possible to add or modify properties to the Object prototype through a malicious template. This may allow attackers to crash the application or execute Arbitrary Code in specific conditions.

Recommendation

Upgrade to version 3.0.8, 4.5.3 or later.

Versions of handlebars prior to 3.0.8 or 4.5.3 are vulnerable to Arbitrary Code Execution. The package's lookup helper fails to properly validate templates, allowing attackers to submit templates that execute arbitrary JavaScript in the system. It is due to an incomplete fix for a previous issue. This vulnerability can be used to run arbitrary code in a server processing Handlebars templates or on a victim's browser (effectively serving as Cross-Site Scripting).

Recommendation

Upgrade to version 3.0.8, 4.5.3 or later.

These are all security issues fixed in the velociraptor-0.76.7.0.git145.b60ef1146-1.1 package on the GA media of openSUSE Tumbleweed.

Root has patched CVE-2026-65903 in the dompurify package for Root:npm. Multiple fixed versions available.

Root has patched GHSA-2cf5-4w76-r9qv in the handlebars package for Root:npm. Multiple fixed versions available.

Root has patched GHSA-39q2-94rc-95cp in the dompurify package for Root:npm. Multiple fixed versions available.

Root has patched GHSA-g9r4-xpmj-mj65 in the handlebars package for Root:npm. Multiple fixed versions available.

Root has patched GHSA-q2c6-c6pm-g3gh in the handlebars package for Root:npm. Multiple fixed versions available.

Root has patched GHSA-q42p-pg8m-cqh6 in the handlebars package for Root:npm. Multiple fixed versions available.