by Kastro CVE-2026-33228
WebReflection flatted — flatted: Prototype Pollution via parse()
Description · from the CVE record
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.
Affected
ProductAffectedFixed inSource
flatted< 3.4.2–CNA
Cluster Observability Operator 1.5.0see advisory1782839279redhat-SADP
Cluster Observability Operator 1.5.0see advisory1782840539redhat-SADP
Cluster Observability Operator 1.5.0see advisory1782839996redhat-SADP
Red Hat Developer Hub 1.8see advisory1776784286redhat-SADP
Red Hat Developer Hub 1.9see advisory1777903262redhat-SADP
Cryostat 4see advisory–redhat-SADP
Logging Subsystem for Red Hat OpenShiftsee advisory–redhat-SADP
Logging Subsystem for Red Hat OpenShiftsee advisory–redhat-SADP
Logging Subsystem for Red Hat OpenShiftsee advisory–redhat-SADP
Logging Subsystem for Red Hat OpenShiftsee advisory–redhat-SADP
Logging Subsystem for Red Hat OpenShiftsee advisory–redhat-SADP
Scores by source
NVD9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
redhat-SADP (CNA)9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
GitHub_M (CNA)8.9CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P
CISA ADPSSVCExploitation: poc · Automatable: yes · Technical impact: total