CVE-2026-4800

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.

PUBLISHED Reserved 2026-03-25 | Published 2026-03-31 | Updated 2026-03-31 | Assigner openjs

Problem types

CWE-94: Improper Control of Generation of Code ('Code Injection')

Product status

Credits

dolevmiz1 reporter

bugbunny-research reporter

M0nd0R reporter

UlisesGascon remediation developer

falsyvalues remediation reviewer

jonchurch remediation reviewer

threalwinky reporter

jdalton remediation reviewer

References

github.com/advisories/GHSA-35jh-r3h4-6jhm

github.com/...ommit/3469357cff396a26c363f8c1b5a91dde28ba4b1c

cna.openjsf.org/security-advisories.html

cve.org (CVE-2026-4800)

nvd.nist.gov (CVE-2026-4800)

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