Read the docs
TI-2026-25647 Aliases CVE-2026-33228GHSA-rf6f-7fwh-wjgh

flatted: Prototype Pollution via parse()

Priority HIGH 80CWE-1321Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
Tampering
Confidentiality · integrity · availability
High · High · High
Fix status
Partial Red Hat: 4 fixed, 3 without a fix

Attack profile from CVSS 4.0 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-915.

Summary

flatted is a circular JSON parser. Prior to version 3.4.2, the parse() function in flatted can use attacker-controlled string values from the parsed JSON as direct array index keys, without validating that they are numeric. Since the internal input buffer is a JavaScript Array, accessing it with the key "__proto__" returns Array.prototype via the inherited getter. This object is then treated as a legitimate parsed value and assigned as a property of the output object, effectively leaking a live reference to Array.prototype to the consumer. Any code that subsequently writes to that property will pollute the global prototype. This issue has been patched in version 3.4.2.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00856 58th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Partial flatted (WebReflection): 3.4.2flatted (npm): 3.4.2Red Hat: 4 advisoriesRed Hat: 4 fixed, 3 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
WebReflectionflattedbefore 3.4.23.4.2Patch availableCNA
—flatted (npm)before 3.4.23.4.2Patch availableGHSA-rf6f-7fwh-wjgh
  • flatted VendorWebReflection Affected before 3.4.2 Fixed in 3.4.2 Patch available CNA
  • flatted (npm) Vendor— Affected before 3.4.2 Fixed in 3.4.2 Patch available GHSA-rf6f-7fwh-wjgh

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:webreflection:flatted:*:*:*:*:*:node.js:*:*before 3.4.2VulnerableWebReflection
  • cpe:2.3:a:webreflection:flatted:*:*:*:*:*:node.js:*:* Versions before 3.4.2 Vulnerable ·WebReflection

Remediation

  • Fix · CNA flatted (WebReflection) Fixed in 3.4.2
  • Fix · GHSA-rf6f-7fwh-wjgh flatted (npm) Fixed in 3.4.2 Advisory →

Red Hat 4 advisories

  • RHSA-2026:86618 Released 2026-10-21 · Red Hat rating Critical
    New container image: rhceph-9.2
    • Red Hat Ceph Storage 9.2 registry.redhat.io/rhceph/rhceph-9-rhel10
  • RHSA-2026:34342 Released 2026-07-01 · Red Hat rating Critical
    Cluster Observability Operator 1.5.0
    • Cluster Observability Operator 1.5 registry.redhat.io/cluster-observability-operator/distributed-tracing-console-plugin-pf4-rhel9, registry.redhat.io/cluster-observability-operator/distributed-tracing-console-plugin-pf5-rhel9, registry.redhat.io/cluster-observability-operator/distributed-tracing-console-plugin-pf6-rhel9 +9
  • RHSA-2026:13826 Released 2026-05-05 · Red Hat rating Critical
    Red Hat Developer Hub 1.9.4 release.
    • Red Hat Developer Hub 1.9 registry.redhat.io/rhdh/rhdh-hub-rhel9, registry.redhat.io/rhdh/rhdh-rhel9-operator
Show 1 more Red Hat advisories
  • RHSA-2026:9742 Released 2026-04-22 · Red Hat rating Critical
    Red Hat Developer Hub 1.8.6 release.
    • Red Hat Developer Hub 1.8 registry.redhat.io/rhdh/rhdh-hub-rhel9, registry.redhat.io/rhdh/rhdh-rhel9-operator

Vendor assessments

Red Hat

Red Hat rating: Critical. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat 3scale API Management Platform 2AffectedNo fix planned: Will not fix
Red Hat Build of KeycloakAffectedNo fix planned: Will not fix
Red Hat Single Sign-On 7AffectedNo fix planned: Will not fix
Cluster Observability Operator 1.5Fixed RHSA-2026:34342
Red Hat Ceph Storage 9.2Fixed RHSA-2026:86618
Red Hat Developer Hub 1.8Fixed RHSA-2026:9742
Red Hat Developer Hub 1.9Fixed RHSA-2026:13826
Not affected: 29 products
  • Cluster Observability Operator 1.5
  • Cryostat 4
  • Logging Subsystem for Red Hat OpenShift
  • Multicluster Engine for Kubernetes
  • Red Hat AMQ Broker 7
  • Red Hat Advanced Cluster Management for Kubernetes 2
  • Red Hat Build of Podman Desktop
  • Red Hat Ceph Storage 9.2
  • Red Hat Data Grid 8
  • Red Hat Developer Hub 1.8
  • Red Hat Developer Hub 1.9
  • Red Hat Directory Server 11
  • Red Hat Directory Server 12
  • Red Hat Directory Server 13
  • Red Hat Enterprise Linux 10
  • Red Hat Enterprise Linux 8
  • Red Hat Enterprise Linux 9
  • Red Hat Fuse 7
  • Red Hat JBoss Enterprise Application Platform 7
  • Red Hat JBoss Enterprise Application Platform 8
  • Red Hat JBoss Enterprise Application Platform Expansion Pack
  • Red Hat OpenShift AI (RHOAI)
  • Red Hat OpenShift Container Platform 4
  • Red Hat Process Automation 7
  • Red Hat Quay 3
  • Red Hat build of Apicurio Registry 2
  • Red Hat build of OptaPlanner 8
  • streams for Apache Kafka 2
  • streams for Apache Kafka 3

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-33228
  2. 2026-10-03 Alias added: GHSA-rf6f-7fwh-wjgh
  3. 2026-10-05 Weakness changed · GHSA-rf6f-7fwh-wjgh
  4. 2026-10-05 5 new references · GHSA-rf6f-7fwh-wjgh
  5. 2026-10-21 Fix available: RHSA-2026:86618 · Red Hat
  6. 2026-10-21 Fix available: Red Hat Ceph Storage 9.2 · Red Hat
  7. 2026-11-05 Fix available: Cluster Observability Operator 1.5 · Red Hat

References

Exploit 1

Patch 1

Advisory 1

Other 7

  • TI-2026-24678 flatted: Unbounded recursion DoS in parse() revive phase CVSS 3.1HIGH 7.5

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences