CVE-2026-4800 is a high-severity (CVSS 8.1) Code Injection vulnerability in lodash. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for lodash — see the affected versions and patch details below.
lodash vulnerable to Code Injection via `_.template` imports key names
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-4800.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
lodashnpmlodash-esnpmlodash-amdnpmDescription
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:
- Validate
importsKeysagainst the existingreForbiddenIdentifierCharsregex (same check already used for thevariableoption) - Replace
assignInWithwithassignWithwhen 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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | lodash | ≥ 4.0.0&&< 4.18.0 | 4.18.0npm install lodash@4.18.0 |
| 📦npm | lodash-es | ≥ 4.0.0&&< 4.18.0 | 4.18.0npm install lodash-es@4.18.0 |
| 📦npm | lodash-amd | ≥ 4.0.0&&< 4.18.0 | 4.18.0npm install lodash-amd@4.18.0 |
| 📦npm | lodash.template | ≥ 4.0.0&&< 4.18.0 | 4.18.0npm install lodash.template@4.18.0 |
Affected Products
lodashlodashlodash-amdlodashlodash-eslodashlodash.templatelodashResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for lodash, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update lodash to 4.18.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-4800 is resolved across your whole dependency graph.
Workarounds
Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
In the context of Red Hat Enterprise Linux, the grafana and grafana-pcp packages execute the affected JavaScript entirely client-side within the user's browser. Consequently, the attack surface is strictly restricted to the local browser environment.
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.Source: Red Hat security advisory for CVE-2026-4800 (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| Cryostat 4 on RHEL 9 | cryostat/cryostat-openshift-console-plugin-rhel9:4.2.0-9 | RHSA-2026:17789 |
| Red Hat Ansible Automation Platform 2.5 for RHEL 8 | automation-gateway-0:2.5.20260715-1.el8ap | RHSA-2026:42078 |
| Red Hat Ansible Automation Platform 2.6 for RHEL 9 | automation-platform-ui-0:2.6.9-1.el9ap | RHSA-2026:24762 |
| Red Hat Data Grid 8.6.1 | lodash | RHSA-2026:22619 |
| Red Hat Enterprise Linux 10 | pcs-0:0.12.1-1.el10_1.3 | RHSA-2026:10713 |
| Red Hat Enterprise Linux 10 | cockpit-0:356.1-1.el10_2 | RHBA-2026:21388 |
| Red Hat Enterprise Linux 10 | pcs-0:0.12.2-3.el10_2.1 | RHSA-2026:19008 |
| Red Hat Enterprise Linux 10 | cockpit-image-builder-0:94.3-1.el10_2 | RHSA-2026:24331 |
Frequently Asked Questions
Is CVE-2026-4800 in your dependencies?
Find it across npm, including transitive dependencies.