Medium
node-handlebars — security advisory
Handlebars provides the power necessary to let users build semantic templates. In versions 4.0.0 through 4.7.8, `resolvePartial()` in the Handlebars runtime resolves partial names via a plain property lookup on `options.partials` without guarding against prototype-chain traversal. When `Object.prototype` has been polluted with a string value whose key matches a partial reference in a template, the polluted string is used as the partial body and rendered without HTML escaping, resulting in reflected or stored XSS. Version 4.7.9 fixes the issue. Some workarounds are available. Apply `Object.freeze(Object.prototype)` early in application startup to prevent prototype pollution. Note: this may break other libraries, and/or use the Handlebars runtime-only build (`handlebars/runtime`), which does not compile templates and reduces the attack surface.
- Products
- node-handlebars
- Affected versions
- 3:4.0.10-5, 3:4.1.0-1, 3:4.5.3-1, 3:4.7.2-1, 3:4.7.6+~4.1.0-2, 3:4.7.7+~4.1.0-1, 3:4.7.9-5
- Fixed versions
- Not specified
- CVEs
- CVE-2026-33916
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 02:07 UTC · Revision 1
Source evidence
Handlebars provides the power necessary to let users build semantic templates. In versions 4.0.0 through 4.7.8, `resolvePartial()` in the Handlebars runtime resolves partial names via a plain property lookup on `options.partials` without guarding against prototype-chain traversal. When `Object.prototype` has been polluted with a string value whose key matches a partial reference in a template, the polluted string is used as the partial body and rendered without HTML escaping, resulting in reflected or stored XSS. Version 4.7.9 fixes the issue. Some workarounds are available. Apply `Object.freeze(Object.prototype)` early in application startup to prevent prototype pollution. Note: this may break other libraries, and/or use the Handlebars runtime-only build (`handlebars/runtime`), which does not compile templates and reduces the attack surface.
osv:UBUNTU-CVE-2026-33916
node-handlebars
Fixed versions: Not specified
node-handlebars
Fixed versions: Not specified
node-handlebars
Fixed versions: Not specified
node-handlebars
Fixed versions: Not specified
node-handlebars
Fixed versions: Not specified
node-handlebars
Fixed versions: Not specified
node-handlebars
Fixed versions: Not specified
Complete source record
{
"id": "f72543d6d99dcbd8b7c7b26a3bbfdc46f9c789bef93901b60fdfbcd73704a38d",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-33916",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-33916",
"summary": "Handlebars provides the power necessary to let users build semantic templates. In versions 4.0.0 through 4.7.8, `resolvePartial()` in the Handlebars runtime resolves partial names via a plain property lookup on `options.partials` without guarding against prototype-chain traversal. When `Object.prototype` has been polluted with a string value whose key matches a partial reference in a template, the polluted string is used as the partial body and rendered without HTML escaping, resulting in reflected or stored XSS. Version 4.7.9 fixes the issue. Some workarounds are available. Apply `Object.freeze(Object.prototype)` early in application startup to prevent prototype pollution. Note: this may break other libraries, and/or use the Handlebars runtime-only build (`handlebars/runtime`), which does not compile templates and reduces the attack surface.",
"evidence": "osv:UBUNTU-CVE-2026-33916",
"products": [
{
"name": {
"value": "node-handlebars",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3:4.0.10-5",
"evidence": "/affected/0/versions"
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{
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"evidence": "/affected/1/versions"
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{
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"evidence": "/affected/1/versions"
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{
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"evidence": "/affected/2/versions"
},
{
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"evidence": "/affected/2/versions"
}
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{
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{
"name": {
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"evidence": "/affected/5/package/name"
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"affected_versions": [
{
"value": "3:4.7.7+~4.1.0-1",
"evidence": "/affected/5/versions"
},
{
"value": "3:4.7.9-5",
"evidence": "/affected/5/versions"
}
]
},
{
"name": {
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"evidence": "/affected/6/package/name"
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"affected_versions": [
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]
}
],
"severity": "medium",
"structured": {
"id": "UBUNTU-CVE-2026-33916",
"aliases": [
"UBUNTU-CVE-2026-33916"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N"
},
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N"
},
{
"type": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
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],
"package": {
"name": "node-handlebars",
"purl": "pkg:deb/ubuntu/node-handlebars?arch=source&distro=bionic",
"ecosystem": "Ubuntu:18.04:LTS"
},
"versions": [
"3:4.0.10-5"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33916.json"
},
"ecosystem_specific": {
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"purl": "pkg:deb/ubuntu/node-handlebars?arch=source&distro=focal",
"ecosystem": "Ubuntu:20.04:LTS"
},
"versions": [
"3:4.1.0-1",
"3:4.5.3-1",
"3:4.7.2-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33916.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "handlebars",
"binary_version": "3:4.7.2-1"
},
{
"binary_name": "libjs-handlebars",
"binary_version": "3:4.7.2-1"
},
{
"binary_name": "libjs-handlebars.runtime",
"binary_version": "3:4.7.2-1"
}
]
}
},
{
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"purl": "pkg:deb/ubuntu/node-handlebars?arch=source&distro=jammy",
"ecosystem": "Ubuntu:22.04:LTS"
},
"versions": [
"3:4.7.6+~4.1.0-2",
"3:4.7.7+~4.1.0-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33916.json"
},
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"ecosystem": "Ubuntu:24.04:LTS"
},
"versions": [
"3:4.7.7+~4.1.0-1"
],
"database_specific": {
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"ecosystem": "Ubuntu:25.10"
},
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"3:4.7.7+~4.1.0-1"
],
"database_specific": {
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},
"ecosystem_specific": {
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{
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"ecosystem": "Ubuntu:26.04:LTS"
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],
"modified": "2026-10-17T12:58:11.075887493Z",
"provider": "osv",
"upstream": [
"CVE-2026-33916"
],
"references": [
"https://ubuntu.com/security/CVE-2026-33916",
"https://www.cve.org/CVERecord?id=CVE-2026-33916",
"https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-2qvq-rjwj-gvw9",
"https://github.com/handlebars-lang/handlebars.js/commit/68d8df5a88e0a26fe9e6084c5c6aaebe67b07da2",
"https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.9"
]
},
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{
"value": "CVE-2026-33916",
"evidence": "/upstream"
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],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 358298,
"published_at": "2026-03-27T21:17:00+00:00"
}