node-handlebars — security advisory
Handlebars provides the power necessary to let users build semantic templates. In versions 4.0.0 through 4.7.8, a crafted object placed in the template context can bypass all conditional guards in `resolvePartial()` and cause `invokePartial()` to return `undefined`. The Handlebars runtime then treats the unresolved partial as a source that needs to be compiled, passing the crafted object to `env.compile()`. Because the object is a valid Handlebars AST containing injected code, the generated JavaScript executes arbitrary commands on the server. The attack requires the adversary to control a value that can be returned by a dynamic partial lookup. Version 4.7.9 fixes the issue. Some workarounds are available. First, use the runtime-only build (`require('handlebars/runtime')`). Without `compile()`, the fallback compilation path in `invokePartial` is unreachable. Second, sanitize context data before rendering: Ensure no value in the context is a non-primitive object that could be passed to a dynamic partial. Third, avoid dynamic partial lookups (`{{> (lookup ...)}}`) when context data is user-controlled.
- Products
- node-handlebars
- Affected versions
- 3:4.7.10-1, 3:4.7.7+~4.1.0-1, 3:4.7.9-1, 3:4.7.9-2, 3:4.7.9-3, 3:4.7.9-4, 3:4.7.9-5, 3:4.7.9-6
- Fixed versions
- 3:4.7.9-1
- CVEs
- CVE-2026-33940
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 17:51 UTC · Revision 2
Source evidence
Handlebars provides the power necessary to let users build semantic templates. In versions 4.0.0 through 4.7.8, a crafted object placed in the template context can bypass all conditional guards in `resolvePartial()` and cause `invokePartial()` to return `undefined`. The Handlebars runtime then treats the unresolved partial as a source that needs to be compiled, passing the crafted object to `env.compile()`. Because the object is a valid Handlebars AST containing injected code, the generated JavaScript executes arbitrary commands on the server. The attack requires the adversary to control a value that can be returned by a dynamic partial lookup. Version 4.7.9 fixes the issue. Some workarounds are available. First, use the runtime-only build (`require('handlebars/runtime')`). Without `compile()`, the fallback compilation path in `invokePartial` is unreachable. Second, sanitize context data before rendering: Ensure no value in the context is a non-primitive object that could be passed to a dynamic partial. Third, avoid dynamic partial lookups (`{{> (lookup ...)}}`) when context data is user-controlled.
osv:DEBIAN-CVE-2026-33940
node-handlebars
Fixed versions: Not specified
node-handlebars
Fixed versions: Not specified
node-handlebars
Fixed versions: 3:4.7.9-1
Complete source record
{
"id": "ef70c7afc6dfe6a16725036776b6f3a6428b74aabe7270b72a46bdea5aa8fc8c",
"url": "https://osv.dev/vulnerability/DEBIAN-CVE-2026-33940",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "DEBIAN-CVE-2026-33940",
"summary": "Handlebars provides the power necessary to let users build semantic templates. In versions 4.0.0 through 4.7.8, a crafted object placed in the template context can bypass all conditional guards in `resolvePartial()` and cause `invokePartial()` to return `undefined`. The Handlebars runtime then treats the unresolved partial as a source that needs to be compiled, passing the crafted object to `env.compile()`. Because the object is a valid Handlebars AST containing injected code, the generated JavaScript executes arbitrary commands on the server. The attack requires the adversary to control a value that can be returned by a dynamic partial lookup. Version 4.7.9 fixes the issue. Some workarounds are available. First, use the runtime-only build (`require('handlebars/runtime')`). Without `compile()`, the fallback compilation path in `invokePartial` is unreachable. Second, sanitize context data before rendering: Ensure no value in the context is a non-primitive object that could be passed to a dynamic partial. Third, avoid dynamic partial lookups (`{{> (lookup ...)}}`) when context data is user-controlled.",
"evidence": "osv:DEBIAN-CVE-2026-33940",
"products": [
{
"name": {
"value": "node-handlebars",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3:4.7.10-1",
"evidence": "/affected/0/versions"
},
{
"value": "3:4.7.7+~4.1.0-1",
"evidence": "/affected/0/versions"
},
{
"value": "3:4.7.9-1",
"evidence": "/affected/0/versions"
},
{
"value": "3:4.7.9-2",
"evidence": "/affected/0/versions"
},
{
"value": "3:4.7.9-3",
"evidence": "/affected/0/versions"
},
{
"value": "3:4.7.9-4",
"evidence": "/affected/0/versions"
},
{
"value": "3:4.7.9-5",
"evidence": "/affected/0/versions"
},
{
"value": "3:4.7.9-6",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "node-handlebars",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3:4.7.10-1",
"evidence": "/affected/1/versions"
},
{
"value": "3:4.7.7+~4.1.0-1",
"evidence": "/affected/1/versions"
},
{
"value": "3:4.7.9-1",
"evidence": "/affected/1/versions"
},
{
"value": "3:4.7.9-2",
"evidence": "/affected/1/versions"
},
{
"value": "3:4.7.9-3",
"evidence": "/affected/1/versions"
},
{
"value": "3:4.7.9-4",
"evidence": "/affected/1/versions"
},
{
"value": "3:4.7.9-5",
"evidence": "/affected/1/versions"
},
{
"value": "3:4.7.9-6",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
"value": "node-handlebars",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "3:4.7.9-1",
"evidence": "/affected/2/ranges"
}
],
"affected_versions": [
{
"value": "3:4.7.7+~4.1.0-1",
"evidence": "/affected/2/versions"
}
]
}
],
"severity": "high",
"structured": {
"id": "DEBIAN-CVE-2026-33940",
"aliases": [
"DEBIAN-CVE-2026-33940"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "node-handlebars",
"purl": "pkg:deb/debian/node-handlebars?arch=source&distro=bookworm",
"ecosystem": "Debian:12"
},
"versions": [
"3:4.7.10-1",
"3:4.7.7+~4.1.0-1",
"3:4.7.9-1",
"3:4.7.9-2",
"3:4.7.9-3",
"3:4.7.9-4",
"3:4.7.9-5",
"3:4.7.9-6"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-33940.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "node-handlebars",
"purl": "pkg:deb/debian/node-handlebars?arch=source&distro=trixie",
"ecosystem": "Debian:13"
},
"versions": [
"3:4.7.10-1",
"3:4.7.7+~4.1.0-1",
"3:4.7.9-1",
"3:4.7.9-2",
"3:4.7.9-3",
"3:4.7.9-4",
"3:4.7.9-5",
"3:4.7.9-6"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-33940.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "3:4.7.9-1"
}
]
}
],
"package": {
"name": "node-handlebars",
"purl": "pkg:deb/debian/node-handlebars?arch=source&distro=forky",
"ecosystem": "Debian:14"
},
"versions": [
"3:4.7.7+~4.1.0-1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-33940.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
],
"modified": "2026-10-27T10:00:52.638229248Z",
"provider": "osv",
"upstream": [
"CVE-2026-33940"
],
"references": [
"https://security-tracker.debian.org/tracker/CVE-2026-33940"
]
},
"related_cves": [
{
"value": "CVE-2026-33940",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 461364,
"published_at": "2026-03-27T22:16:21.03+00:00"
}