CVE-2021-33591Network attack vector

Code execution via exposed remote debugging port

Published May 28, 2021 · Updated Aug 3, 2024

Active debug code in NAVER Series PC Comic Viewer 1.0.14.0 and earlier allows remote attackers to execute code via crafted HTML. The application leaves a remote debugging port exposed, but NAVER has not published the port, protocol, or request flow that turns the crafted page into code execution. Exploitation requires user interaction, and successful code runs with the viewer user's privileges.

CVSS severity8.8
High
EPSS probability1.59%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Active debug code in NAVER Series PC Comic Viewer 1.0.14.0 and earlier allows remote attackers to execute code via crafted HTML. The application leaves a remote debugging port exposed, but NAVER has not published the port, protocol, or request flow that turns the crafted page into code execution. Exploitation requires user interaction, and successful code runs with the viewer user's privileges.

The record

CVE
CVE-2021-33591
Published
May 28, 2021
Updated
Aug 3, 2024
Vendor
NAVER Corporation
Product
NAVER Series PC Comic Viewer
Classifications
CWE-489, CAPEC-121, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 28, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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=unspecified <=1.0.14.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

NAVER Corporation · NAVER Series PC Comic Viewerversion=unspecified <=1.0.14.0

Published CVSS scores

8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
6.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:P

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-489Active Debug Code
CAPEC-121Exploit Non-Production Interfaces
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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