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ImmutableApplication · Immutable Js

CVE-2026-59879

HIGH · 7.5 CVSS v3.1 Published 2026-07-08
Fix available
A fix is available. Upgrade to 4.3.9 / 5.1.8 or later.
See remediation →
84/100
Remediation priority · High
Public exploit Remotely reachable No privileges Zero-click Patch available 6 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Immutable.js provides many Persistent Immutable data structures. Prior to 4.3.9 and 5.1.8, List#set, List#setSize, List#setIn, List#updateIn, and the functional set, setIn, and updateIn mishandle an index or size in the range 2 ** 30 to 2 ** 31 in setListBounds in src/List.js, causing an empty List to enter an uncatchable infinite loop, a populated List to allocate without bound until process abort, or setSize to silently wrap large values. This issue is fixed in versions 4.3.9 and 5.1.8.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Immutable.js versions prior to 4.3.9 and 5.1.8 have a vulnerability in List manipulation functions (set, setSize, setIn, updateIn) where indices or sizes between 2^30 and 2^31 are mishandled in setListBounds. This causes either an uncatchable infinite loop with empty Lists, unbounded memory allocation with populated Lists until process abort, or silent integer wraparound with setSize, resulting in denial of service.

MitigationUpgrade Immutable.js to version 4.3.9, 5.1.8, or later to patch the vulnerable List bounds handling code.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
ImmutableApplication
Affected:< 4.3.9>= 5.0.0, < 5.1.8

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the installed Immutable.js version
    Check package.json, package-lock.json, or run 'npm list immutable' or 'yarn list immutable' in your project directory. If using a bundler, check the resolved version in node_modules/immutable/package.json under the 'version' field.
    Affected if The version is below 4.3.9, or is 5.0.0 through 5.1.7 inclusive.
  2. Locate List manipulation usage in codebase
    Search your codebase for calls to Immutable.List methods: .set(, .setSize(, .setIn(, or .updateIn(. Use grep or IDE search across your JavaScript/TypeScript source files.
    Affected if Any of these four methods are used with index or size parameters derived from user input.
  3. Trace index/size parameter sources
    For each found call to set, setSize, setIn, or updateIn, review the code to determine if the index or size argument could be controlled by external input (query parameters, API payloads, user files, or data from external services).
    Affected if Untrusted input can reach these methods without validation that indices are below 2^30.
  4. Verify input validation on List indices
    If List manipulation methods receive user-controlled indices, check if there is explicit bounds validation ensuring indices are less than 2^30 (approximately 1,073,741,824) before the Immutable.js call.
    Affected if No validation exists and indices between 2^30 and 2^31 can reach the vulnerable methods.

You are affected if your environment runs a vulnerable Immutable.js version (below 4.3.9 or 5.0.0-5.1.7) AND your application passes potentially large index or size values to List.set(), List.setSize(), List.setIn(), or List.updateIn() without validating they stay below 2^30.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 4.3.9 / 5.1.8 or later
Fixed in 4.3.95.1.8
Vendor patch github.com →
Interim mitigation

Upgrade Immutable.js to version 4.3.9, 5.1.8, or later to patch the vulnerable List bounds handling code.

Recommended fix High confidence

immutable.js version 4.3.9 (for 4.x users) or 5.1.8 (for 5.x users)

  1. 1. Identify the current version of immutable-js in your project by checking package.json or package-lock.json
  2. 2. If using version < 4.3.9: run 'npm install immutable@^4.3.9' or 'yarn add immutable@^4.3.9' to upgrade to the 4.x stable fix
  3. 3. If using version >= 5.0.0 and < 5.1.8: run 'npm install immutable@^5.1.8' or 'yarn add immutable@^5.1.8' to upgrade to the 5.x stable fix
  4. 4. Run your test suite to verify the upgrade does not break existing functionality
  5. 5. Rebuild and redeploy your application
Caveat Major version upgrades (e.g., 4.x to 5.x) may include breaking API changes; review the Immutable.js changelog before upgrading between major versions

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Immutable Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing4.0 h
  • Review / QA2.0 h
9.0 hours of engineering $1,540
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-59879 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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