VulnerabilityModified

CVE-2026-4800

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.

CRITICAL 9.8EPSS 2.76%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (2.76%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

Description

Impact: The 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. 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. Workarounds: Do not pass untrusted input as key names in options.imports. Only use developer-controlled, static key names.

CVSS 3.1: 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS: 2.76% probability · 85th percentile
CISA KEV: Not listed
Weakness: CWE-94
Affected: lodash/lodash · lodash/lodash-amd · lodash/lodash-es · lodash/lodash.template
Source: ce714d77-add3-4f53-aff5-83d477b104bb

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.