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Public proof of conceptFix available

CVE-2026-59880

A public proof of concept exists; no exploitation attested.

  • Published2026-07-08
  • Fixed in5.1.8 · 4.3.9 · 3.8.4
  • WeaknessCWE-407

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

Immutable.js provides many Persistent Immutable data structures. Prior to 4.3.9 and 5.1.8, Immutable.Map and Immutable.Set keep keys that share the same 32-bit hash in a HashCollisionNode collision bucket that is scanned linearly, allowing an attacker who controls keys inserted into a Map, such as through Immutable.Map(obj), Immutable.fromJS(obj), state.merge(userObject), or mergeDeep, to craft many colliding keys and degrade insertion and lookup to consume disproportionate CPU. This issue is fixed in versions 4.3.9 and 5.1.8.

Timeline

dates in UTC
  1. 2026-07-0816:16CVE publishedNVD

Versions per branch

NVD · OSV
Immutable-js immutable
BranchAffectedFixed in
5.x≥ 5.0.0, < 5.1.85.1.8
5.x≥ 5.0.0-beta.1, < 5.1.85.1.8
4.3< 4.3.94.3.9
4.x≥ 4.0.0-beta.1, < 4.3.94.3.9
3.8< 3.8.43.8.4

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Products declared by the CNA1 product

As GitHub_M, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

  • immutable-js
    Affected
    • = < 4.3.9no fix stated
    • = >= 5.0.0-beta.1, < 5.1.8no fix stated

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2026-07-08

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • @rootio/immutableRoot:npmall versions · fixed in 3.8.4-root.io.2
  • @rootio/immutableRoot:npmall versions · fixed in 3.7.6-root.io.3
  • @rootio/immutableRoot:npmall versions · fixed in 3.7.6-root.io.4
  • @rootio/immutableRoot:npmall versions · fixed in 3.8.3-root.io.2
  • @rootio/immutableRoot:npmall versions · fixed in 3.8.4-root.io.1
  • @rootio/immutableRoot:npmall versions · fixed in 4.0.0-rc.12-root.io.1
  • @rootio/immutableRoot:npmall versions · fixed in 4.0.0-root.io.1
  • @rootio/immutableRoot:npmall versions · fixed in 4.0.0-root.io.2

89 more package ranges on OSV.dev

Full record on NVD

Fix

  1. Update Immutable-js immutable to 5.1.8 · 4.3.9 · 3.8.4

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

  • CISA-ADPSSVC decisionpoc2026-07-08
  • CNACVSS 4.08.7known since 2026-10-23
  • NVDCVSS 3.17.5read 2026-10-23
  • CNAweakness (CWE)CWE-407known since 2026-10-23
  • FIRST EPSSEPSS score0.7 %2026-11-09
  • OSVaffected packages—
  • GitHub AdvisoriesadvisoryHIGH2026-07-21

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 4.0 vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Published
2026-07-08
Last Modified
2026-07-10
NVD status
Analyzed
GitHub Advisory
GHSA-xvcm-6775-5m9r

Frequently asked questions

What is CVE-2026-59880?

Immutable.js provides many Persistent Immutable data structures. Prior to 4.3.9 and 5.1.8, Immutable.Map and Immutable.Set keep keys that share the same 32-bit hash in a HashCollisionNode collision bucket that is scanned linearly, allowing an attacker who controls keys inserted into a Map, such as through Immutable.Map(obj), Immutable.fromJS(obj), state.merge(userObject), or mergeDeep, to craft many colliding keys and degrade insertion and lookup to consume disproportionate CPU. This issue is fixed in versions 4.3.9 and 5.1.8.

Is CVE-2026-59880 actively exploited?

A proof-of-concept exploit exists for CVE-2026-59880, but active exploitation has not been confirmed at this time.

What is the CVSS score for CVE-2026-59880?

CVE-2026-59880 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

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