CVE-2020-8125Public exploitNetwork attack vector

Code execution via unsafe __proto__ assignment

Published Feb 4, 2020 · Updated Aug 4, 2024

Prototype pollution in Luke Edwards Klona 1.1.0 and earlier allows remote attackers to execute code or interrupt applications. The object-cloning loop assigns an enumerable proto key directly to a fresh object, invoking the prototype setter instead of creating a data property. Exploitation requires an application to pass attacker-controlled objects into Klona and then consume a polluted property through a code-execution or denial-of-service gadget.

CVSS severity9.8
Critical
EPSS probability4.12%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Prototype pollution in Luke Edwards Klona 1.1.0 and earlier allows remote attackers to execute code or interrupt applications. The object-cloning loop assigns an enumerable proto key directly to a fresh object, invoking the prototype setter instead of creating a data property. Exploitation requires an application to pass attacker-controlled objects into Klona and then consume a polluted property through a code-execution or denial-of-service gadget.

The record

CVE
CVE-2020-8125
Published
Feb 4, 2020
Updated
Aug 4, 2024
Vendor
Luke Edwards
Product
Klona
Classifications
CWE-20
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 4, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Fixed Version: v1.1.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Luke Edwards · Klonaversion=Fixed Version: v1.1.1

Published CVSS scores

9.8GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-20Improper Input Validation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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