CVE-2026-4800

lodash vulnerable to Code Injection via imports key names

Published Mar 31, 2026 · corrected/updated Oct 17, 2026 · Red Hat lodash · evidence confidence high

### Impact The fix for [CVE-2021-23337](https://github.com/advisories/GHSA-35jh-r3h4-6jhm) added validation for the option in but did not apply the same validation to key names. Both paths flow into the same constructor sink. When an application passes untrusted input as key names, an attacker can inject default-parameter expressions that execute arbitrary code at template compilation time. Additionally, uses to merge imports, which enumerates inherited properties via . If has been polluted by any other vector, the polluted keys are copied into the imports object and passed to . ### Patches Users should upgrade to version 4.18.0. The fix applies two changes: 1. Validate against the existing regex (same check already used for the option) 2. Replace with when merging imports, so only own properties are enumerated ### Workarounds Do not pass untrusted input as key names in . Only use developer-controlled, static key names.

Grounded briefings

Catalog interpretations for three audiences. Each brief cites ingested metadata and the original advisories below. They are not independent research and they do not invent exploit steps.

Executive

CVE-2026-4800 is a critical public vulnerability record for Red Hat lodash. It is not currently listed in the CISA Known Exploited catalog. Check the linked vendor or CERT advisories for patch status. This summary is a catalog interpretation of the ingested metadata and cites the original advisories below.

System administrator

Identify whether Red Hat lodash is in your estate, then compare installed versions with the affected ranges. Affected packages or ranges on record: lodash/lodash; lodash/lodash-amd; lodash/lodash-es; lodash/lodash.template. Check the linked vendor or CERT advisories for patch status. Prefer the vendor or distribution advisory linked in Sources before changing production systems. This is a catalog interpretation, not a runbook.

Security analyst

Signals on file: CVSS 9.8, EPSS 2.6%. It is not currently listed in the CISA Known Exploited catalog. Weakness classes: CWE-94. Sources contributing to this record: circl, csaf, cve_org, epss. Public exploit references, when present, are outbound links only and are not proof of active exploitation. This is a catalog interpretation of stored metadata.

Exploitation and remediation

Exploitation evidence
Not listed as known exploited in CISA KEV. Not in CISA KEV or VulnCheck KEV.
Patch and remediation
No required-action text is stored yet. Use the vendor or CERT links in Sources for patch availability.
Safe detection guidance
Compare installed versions with the affected ranges below and verify the advisory from the original publisher. This site stores metadata and outbound links only; it does not ship exploit code or proof-of-concept payloads.

Code

The project this record applies to. Exploit listings stay in References.

Repository · github.com

Timeline

Detection, updates, and resolution for this record.

Mar 31, 2026 · NIST NVD
Detected
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, and 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. Add
Oct 15, 2026 · NIST NVD
Updated
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, and 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. Add
Oct 17, 2026 · GitHub Advisory Database
Fix available
lodash fixed in 4.18.0; lodash-es fixed in 4.18.0; lodash-amd fixed in 4.18.0; lodash.template fixed in 4.18.0
Oct 17, 2026 · GitHub Advisory Database
Fix available
lodash fixed in 4.18.0
Oct 17, 2026 · GitHub Advisory Database
Fix available
lodash-es fixed in 4.18.0
Oct 17, 2026 · GitHub Advisory Database
Fix available
lodash-amd fixed in 4.18.0
Oct 17, 2026 · GitHub Advisory Database
Fix available
lodash.template fixed in 4.18.0
Oct 17, 2026 · GitHub Advisory Database
Updated
### Impact The fix for [CVE-2021-23337](https://github.com/advisories/GHSA-35jh-r3h4-6jhm) added validation for the option in but did not apply the same validation to key names. Both paths flow into the same constructor sink. When an application passes untrusted input as key names, an attacker can inject default-parameter expressions that execute arbitrary code at template compilation time. Additi

Affected

cpe lodash/lodashversion unspecified
cpe lodash/lodash-amdversion unspecified
cpe lodash/lodash-esversion unspecified
cpe lodash/lodash.templateversion unspecified
npm lodash4.0.0 → 4.18.0
npm lodash-amd4.0.0 → 4.18.0
npm lodash-es4.0.0 → 4.18.0
npm lodash.template4.0.0 → 4.18.0
vendor lodash lodashversion unspecified
vendor lodash lodash-amdversion unspecified
vendor lodash lodash-esversion unspecified
vendor lodash lodash.templateversion unspecified

Sources

CIRCL Vulnerability LookupVulnerability recordCVE-2026-4800
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, and both paths flow into the same Function() constructor sink. When an application passes untrusted input as options.imports key n
vulnerability.circl.lu
CSAF AdvisoriesVendor advisoryRHSA-2026:9742:CVE-2026-4800
A flaw was found in lodash. 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. Additionally, _.template uses assignInWith
security.access.redhat.com
CVE.orgVulnerability recordCVE-2026-4800
Official CVE identifier
cve.org
FIRST EPSSExploitation probabilityCVE-2026-4800
30-day exploitation probability 2.6%
first.org
GitHub Advisory DatabasePackage advisoryGHSA-r5fr-rjxr-66jc
GitHub Advisory Database record mirrored by OSV.
github.com
NIST NVDVulnerability recordCVE-2026-4800
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, and both paths flow into the same Function() constructor sink. When an application passes untrusted input as options.imports key n
nvd.nist.gov
OpenSSF OSV / OSV ScannerPackage advisoryGHSA-r5fr-rjxr-66jc
lodash vulnerable to Code Injection via imports key names
osv.dev