GHSA-R5FR-RJXR-66JC
Vulnerability from github – Published: 2026-04-01 23:51 – Updated: 2026-04-01 23:51
VLAI?
Summary
lodash vulnerable to Code Injection via `_.template` imports key names
Details
Impact
The fix for CVE-2021-23337 added validation for the variable option in _.template but did not apply the same validation to options.imports key names. Both paths flow into the same Function() constructor sink.
When an application passes untrusted input as options.imports key names, an attacker can inject default-parameter expressions that execute arbitrary code at template compilation time.
Additionally, _.template uses assignInWith to merge imports, which enumerates inherited properties via for..in. If Object.prototype has been polluted by any other vector, the polluted keys are copied into the imports object and passed to Function().
Patches
Users should upgrade to version 4.18.0.
The fix applies two changes:
1. Validate importsKeys against the existing reForbiddenIdentifierChars regex (same check already used for the variable option)
2. Replace assignInWith with assignWith when merging imports, so only own properties are enumerated
Workarounds
Do not pass untrusted input as key names in options.imports. Only use developer-controlled, static key names.
Severity ?
8.1 (High)
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 4.17.23"
},
"package": {
"ecosystem": "npm",
"name": "lodash"
},
"ranges": [
{
"events": [
{
"introduced": "4.0.0"
},
{
"fixed": "4.18.0"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 4.17.23"
},
"package": {
"ecosystem": "npm",
"name": "lodash-es"
},
"ranges": [
{
"events": [
{
"introduced": "4.0.0"
},
{
"fixed": "4.18.0"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 4.17.23"
},
"package": {
"ecosystem": "npm",
"name": "lodash-amd"
},
"ranges": [
{
"events": [
{
"introduced": "4.0.0"
},
{
"fixed": "4.18.0"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "npm",
"name": "lodash.template"
},
"ranges": [
{
"events": [
{
"introduced": "4.0.0"
},
{
"fixed": "4.18.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-4800"
],
"database_specific": {
"cwe_ids": [
"CWE-94"
],
"github_reviewed": true,
"github_reviewed_at": "2026-04-01T23:51:12Z",
"nvd_published_at": "2026-03-31T20:16:29Z",
"severity": "HIGH"
},
"details": "### Impact\n\nThe fix for [CVE-2021-23337](https://github.com/advisories/GHSA-35jh-r3h4-6jhm) added validation for the `variable` option in `_.template` but did not apply the same validation to `options.imports` key names. Both paths flow into the same `Function()` constructor sink.\n\nWhen an application passes untrusted input as `options.imports` key names, an attacker can inject default-parameter expressions that execute arbitrary code at template compilation time.\n\nAdditionally, `_.template` uses `assignInWith` to merge imports, which enumerates inherited properties via `for..in`. If `Object.prototype` has been polluted by any other vector, the polluted keys are copied into the imports object and passed to `Function()`.\n\n### Patches\n\nUsers should upgrade to version 4.18.0.\n\nThe fix applies two changes:\n1. Validate `importsKeys` against the existing `reForbiddenIdentifierChars` regex (same check already used for the `variable` option)\n2. Replace `assignInWith` with `assignWith` when merging imports, so only own properties are enumerated\n\n### Workarounds\n\nDo not pass untrusted input as key names in `options.imports`. Only use developer-controlled, static key names.",
"id": "GHSA-r5fr-rjxr-66jc",
"modified": "2026-04-01T23:51:12Z",
"published": "2026-04-01T23:51:12Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/lodash/lodash/security/advisories/GHSA-r5fr-rjxr-66jc"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-4800"
},
{
"type": "WEB",
"url": "https://github.com/lodash/lodash/commit/3469357cff396a26c363f8c1b5a91dde28ba4b1c"
},
{
"type": "WEB",
"url": "https://cna.openjsf.org/security-advisories.html"
},
{
"type": "ADVISORY",
"url": "https://github.com/advisories/GHSA-35jh-r3h4-6jhm"
},
{
"type": "PACKAGE",
"url": "https://github.com/lodash/lodash"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
],
"summary": "lodash vulnerable to Code Injection via `_.template` imports key names"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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