Regular Expression Denial of Service (ReDoS) in lodash

All versions of package lodash prior to 4.17.21 are vulnerable to Regular Expression Denial of Service (ReDoS) via the toNumber, trim and trimEnd functions.

Steps to reproduce (provided by reporter Liyuan Chen): ```js var lo = require('lodash');

function buildblank(n) { var ret = 1 for (var i = 0; i < n; i++) { ret += " } return ret +1"; } var s = buildblank(50000) var time0 = Date.now(); lo.trim(s) var timecost0 = Date.now() - time0; console.log("timecost0: + time_cost0); var time1 = Date.now(); lo.toNumber(s) var time_cost1 = Date.now() - time1; console.log(timecost1: " + timecost1); var time2 = Date.now(); lo.trimEnd(s); var timecost2 = Date.now() - time2; console.log("timecost2: " + time_cost2); ```

Command Injection in lodash

lodash versions prior to 4.17.21 are vulnerable to Command Injection via the template function.

Withdrawn: Arbitrary code execution in lodash

Withdrawn

GitHub has chosen to publish this CVE as a withdrawn advisory due to it not being a security issue. See this issue for more details.

CVE description

"** DISPUTED ** A command injection vulnerability in Lodash 4.17.21 allows attackers to achieve arbitrary code execution via the template function. This is a different parameter, method, and version than CVE-2021-23337. NOTE: the vendor's position is that it's the developer's responsibility to ensure that a template does not evaluate code that originates from untrusted input.

lodash vulnerable to Prototype Pollution via array path bypass in `_.unset` and `_.omit`

Impact

Lodash versions 4.17.23 and earlier are vulnerable to prototype pollution in the _.unset and _.omit functions. The fix for CVE-2025-13465 only guards against string key members, so an attacker can bypass the check by passing array-wrapped path segments. This allows deletion of properties from built-in prototypes such as Object.prototype, Number.prototype, and String.prototype.

The issue permits deletion of prototype properties but does not allow overwriting their original behavior.

Patches

This issue is patched in 4.18.0.

Workarounds

None. Upgrade to the patched version.

Prototype Pollution in lodash

Versions of lodash prior to 4.17.19 are vulnerable to Prototype Pollution. The functions pick, set, setWith, update, updateWith, and zipObjectDeep allow a malicious user to modify the prototype of Object if the property identifiers are user-supplied. Being affected by this issue requires manipulating objects based on user-provided property values or arrays.

This vulnerability causes the addition or modification of an existing property that will exist on all objects and may lead to Denial of Service or Code Execution under specific circumstances.

lodash vulnerable to Code Injection via `_.template` imports key names

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.

Lodash has Prototype Pollution Vulnerability in `_.unset` and `_.omit` functions

Impact

Lodash versions 4.0.0 through 4.17.22 are vulnerable to prototype pollution in the _.unset and _.omit functions. An attacker can pass crafted paths which cause Lodash to delete methods from global prototypes.

The issue permits deletion of properties but does not allow overwriting their original behavior.

Patches

This issue is patched on 4.17.23.

Allocation of Resources Without Limits or Throttling

Prototype pollution attack (lodash)