CVE-2026-4800

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.

The pcs packages provide a command-line configuration system for the Pacemaker and Corosync utilities.

Security Fix(es):

• lodash: lodash: Arbitrary code execution via untrusted input in template imports (CVE-2026-4800)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

The pcs packages provide a command-line configuration system for the Pacemaker and Corosync utilities.

Security Fix(es):

• lodash: lodash: Arbitrary code execution via untrusted input in template imports (CVE-2026-4800)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

The image-builder-frontend generates custom images suitable for deploying systems or uploading to the cloud. It integrates into Cockpit as a frontend for osbuild.

Security Fix(es):

• lodash: prototype pollution in _.unset and _.omit functions (CVE-2025-13465)

• lodash: lodash: Arbitrary code execution via untrusted input in template imports (CVE-2026-4800)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Root has patched CVE-2026-4800 in the lodash package for Root:npm. Multiple fixed versions available.

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. Additionally, _.template uses assignInWith to merge imports, which enumerates inherited properties via for..in, so if Object.prototype has been polluted by another vector the polluted keys are copied into the imports object and passed to Function(). The issue is fixed in 4.18.1 for lodash, lodash-es, lodash-amd, and lodash.template. As a workaround, do not pass untrusted input as key names in options.imports; use only developer-controlled, static key names.

The pcs packages provide a command-line configuration system for the Pacemaker and Corosync utilities.

Security Fix(es):

• lodash: lodash: Arbitrary code execution via untrusted input in template imports (CVE-2026-4800)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

The pcs packages provide a command-line configuration system for the Pacemaker and Corosync utilities.

Security Fix(es):

• lodash: lodash: Arbitrary code execution via untrusted input in template imports (CVE-2026-4800)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

The pcs packages provide a command-line configuration system for the Pacemaker and Corosync utilities.

Security Fix(es):

• lodash: lodash: Arbitrary code execution via untrusted input in template imports (CVE-2026-4800)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

TuxCare rebuilt 11 packages to address 2 CVEs. Fixed in 3.2.0-tuxcare.2.

TuxCare rebuilt lodash to address 2 CVEs. Fixed in 4.17.15-tuxcare.7.

TuxCare rebuilt lodash to address 3 CVEs. Fixed in 4.17.21-tuxcare.1.

TuxCare rebuilt lodash to address 1 CVE. Fixed in 1.3.1-tuxcare.2.

TuxCare rebuilt 7 packages to address 3 CVEs. Fixed in 3.2.0-tuxcare.2.

TuxCare rebuilt lodash to address 2 CVEs. Fixed in 4.17.11-tuxcare.2.

TuxCare rebuilt lodash to address 4 CVEs. Fixed in 4.17.5-tuxcare.3.

TuxCare rebuilt lodash-es to address 7 CVEs. Fixed in 4.17.11-tuxcare.1.

TuxCare rebuilt lodash-es to address 3 CVEs. Fixed in 4.17.21-tuxcare.1.

TuxCare rebuilt lodash-es to address 6 CVEs. Fixed in 4.17.15-tuxcare.1.

TuxCare rebuilt 11 packages to address 1 CVE. Fixed in 4.5.0-tuxcare.6.

TuxCare rebuilt lodash to address 4 CVEs. Fixed in 4.17.23-tuxcare.1.

TuxCare rebuilt lodash.isequal to address 7 CVEs. Fixed in 4.5.0-tuxcare.9.

TuxCare rebuilt lodash.template to address 1 CVE. Fixed in 4.5.0-tuxcare.12.

CVE-2026-4631, Cockpit's remote login feature passes user-supplied hostnames and usernames from the web interface to the SSH client without validation or sanitization. An attacker with network access to the Cockpit web service can craft a single HTTP request to the login endpoint that injects malicious SSH options or shell commands, achieving code execution on the Cockpit host without valid credentials. The injection occurs during the authentication flow before any credential verification takes place, meaning no login is required to exploit the vulnerability. CVE-2026-4800, lodash vulnerable to Code Injection via _.template imports key names CVE-2026-4802, A flaw was found in Cockpit. This vulnerability allows a remote attacker to achieve arbitrary command execution on the host by exploiting unsanitized user-controlled parameters within crafted links in the system logs user interface (UI). An attacker can inject shell metacharacters and command substitutions into these parameters, leading to the execution of arbitrary shell commands on the affected system. This could result in a complete system compromise.

It was discovered that Lodash was vulnerable to a prototype pollution issue in the zipObjectDeep function. An attacker could possibly use this issue to modify application behavior. This issue only affected Ubuntu 18.04 LTS and Ubuntu 20.04 LTS. (CVE-2020-8203)

Liyuan Chen discovered that Lodash was vulnerable to a regular expression denial of service issue in the toNumber, trim, and trimEnd functions. An attacker could possibly use this issue to consume excessive system resources, resulting in a denial of service. This issue only affected Ubuntu 18.04 LTS and Ubuntu 20.04 LTS. (CVE-2020-28500)

Marc Hassan discovered that Lodash did not properly sanitize input to the template function. An attacker could possibly use this issue to inject and execute arbitrary commands. This issue only affected Ubuntu 16.04 LTS, Ubuntu 18.04 LTS, and Ubuntu 20.04 LTS. (CVE-2021-23337)

It was discovered that Lodash was vulnerable to a prototype pollution issue in the unset and omit functions. An attacker could possibly use this issue to delete properties from global prototypes, resulting in security restrictions being bypassed. This issue only affected Ubuntu 18.04 LTS, Ubuntu 20.04 LTS, Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and Ubuntu 25.10. (CVE-2025-13465)

It was discovered that Lodash was vulnerable to a prototype pollution issue in the unset and omit functions. An attacker could possibly use this issue to delete properties from built-in prototypes, resulting in security restrictions being bypassed. This issue only affected Ubuntu 18.04 LTS, Ubuntu 20.04 LTS, Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, Ubuntu 25.10, and Ubuntu 26.04 LTS. (CVE-2026-2950)

It was discovered that Lodash did not properly validate certain inputs to the template function. An attacker could possibly use this issue to inject malicious code during template processing, resulting in arbitrary code execution. (CVE-2026-4800)