You signed in with another tab or window. Reload to refresh your session.You signed out in another tab or window. Reload to refresh your session.You switched accounts on another tab or window. Reload to refresh your session.Dismiss alert
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.
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 importsKeys against the existing reForbiddenIdentifierChars regex (same check already used for the variable option)
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.
Fixes a ReferenceError issue in lodashlodash-eslodash-amd and lodash.template when using the template and fromPairs functions from the modular builds. See #6167 (comment)
These defects were related to how lodash distributions are built from the main branch using https://github.com/lodash-archive/lodash-cli. When internal dependencies change inside lodash functions, equivalent updates need to be made to a mapping in the lodash-cli. (hey, it was ahead of its time once upon a time!). We know this, but we missed it in the last release. It's the kind of thing that passes in CI, but fails bc the build is not the same thing you tested.
There is no diff on main for this, but you can see the diffs for each of the npm packages on their respective branches:
_.unset / _.omit: Fixed prototype pollution via constructor/prototype path traversal (GHSA-f23m-r3pf-42rh, fe8d32e). Previously, array-wrapped path segments and primitive roots could bypass the existing guards, allowing deletion of properties from built-in prototypes. Now constructor and prototype are blocked unconditionally as non-terminal path keys, matching baseSet. Calls that previously returned true and deleted the property now return false and leave the target untouched.
_.template: Fixed code injection via imports keys (GHSA-r5fr-rjxr-66jc, CVE-2026-4800, 879aaa9). Fixes an incomplete patch for CVE-2021-23337. The variable option was validated against reForbiddenIdentifierChars but importsKeys was left unguarded, allowing code injection via the same Function() constructor sink. imports keys containing forbidden identifier characters now throw "Invalid imports option passed into _.template".
Docs
Add security notice for _.template in threat model and API docs (#6099)
Document lower > upper behavior in _.random (#6115)
We have also regenerated and published a select number of the lodash.* modular packages.
These modular packages had fallen out of sync significantly from the minor/patch updates to lodash. Specifically, we have brought the following packages up to parity w/ the latest lodash release because they have had CVEs on them in the past:
A heads-up, this is a breaking change and it might affect your current performance baseline a bit. But here's the exciting part - it's packed with new, cool features and promises improved result stability 🥳! Curious about what's new? Visit our releases page to delve into all the awesome details about this new version.
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
dependenciesPull requests that update a dependency file
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
This PR contains the following updates:
4.17.23→4.18.1Warning
Some dependencies could not be looked up. Check the Dependency Dashboard for more information.
GitHub Vulnerability Alerts
CVE-2026-2950
Impact
Lodash versions 4.17.23 and earlier are vulnerable to prototype pollution in the
_.unsetand_.omitfunctions. 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 asObject.prototype,Number.prototype, andString.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.
CVE-2026-4800
Impact
The fix for CVE-2021-23337 added validation for the
variableoption in_.templatebut did not apply the same validation tooptions.importskey names. Both paths flow into the sameFunction()constructor sink.When an application passes untrusted input as
options.importskey names, an attacker can inject default-parameter expressions that execute arbitrary code at template compilation time.Additionally,
_.templateusesassignInWithto merge imports, which enumerates inherited properties viafor..in. IfObject.prototypehas been polluted by any other vector, the polluted keys are copied into the imports object and passed toFunction().Patches
Users should upgrade to version 4.18.0.
The fix applies two changes:
importsKeysagainst the existingreForbiddenIdentifierCharsregex (same check already used for thevariableoption)assignInWithwithassignWithwhen merging imports, so only own properties are enumeratedWorkarounds
Do not pass untrusted input as key names in
options.imports. Only use developer-controlled, static key names.Release Notes
lodash/lodash (lodash)
v4.18.1Compare Source
Bugs
Fixes a
ReferenceErrorissue inlodashlodash-eslodash-amdandlodash.templatewhen using thetemplateandfromPairsfunctions from the modular builds. See #6167 (comment)These defects were related to how lodash distributions are built from the main branch using https://github.com/lodash-archive/lodash-cli. When internal dependencies change inside lodash functions, equivalent updates need to be made to a mapping in the lodash-cli. (hey, it was ahead of its time once upon a time!). We know this, but we missed it in the last release. It's the kind of thing that passes in CI, but fails bc the build is not the same thing you tested.
There is no diff on main for this, but you can see the diffs for each of the npm packages on their respective branches:
lodash: lodash/lodash@4.18.0-npm...4.18.1-npmlodash-es: lodash/lodash@4.18.0-es...4.18.1-eslodash-amd: lodash/lodash@4.18.0-amd...4.18.1-amdlodash.templatelodash/lodash@4.18.0-npm-packages...4.18.1-npm-packagesv4.18.0Compare Source
v4.18.0
Full Changelog: lodash/lodash@4.17.23...4.18.0
Security
_.unset/_.omit: Fixed prototype pollution viaconstructor/prototypepath traversal (GHSA-f23m-r3pf-42rh, fe8d32e). Previously, array-wrapped path segments and primitive roots could bypass the existing guards, allowing deletion of properties from built-in prototypes. Nowconstructorandprototypeare blocked unconditionally as non-terminal path keys, matchingbaseSet. Calls that previously returnedtrueand deleted the property now returnfalseand leave the target untouched._.template: Fixed code injection viaimportskeys (GHSA-r5fr-rjxr-66jc, CVE-2026-4800, 879aaa9). Fixes an incomplete patch for CVE-2021-23337. Thevariableoption was validated againstreForbiddenIdentifierCharsbutimportsKeyswas left unguarded, allowing code injection via the sameFunction()constructor sink.importskeys containing forbidden identifier characters now throw"Invalid imports option passed into _.template".Docs
_.templatein threat model and API docs (#6099)lower > upperbehavior in_.random(#6115)_.compactjsdoc (#6090)lodash.*modular packagesDiff
We have also regenerated and published a select number of the
lodash.*modular packages.These modular packages had fallen out of sync significantly from the minor/patch updates to lodash. Specifically, we have brought the following packages up to parity w/ the latest lodash release because they have had CVEs on them in the past:
Configuration
📅 Schedule: Branch creation - "" in timezone Asia/Shanghai, Automerge - At any time (no schedule defined).
🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.
♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.
🔕 Ignore: Close this PR and you won't be reminded about this update again.
This PR was generated by Mend Renovate. View the repository job log.