CVE-2021-35036Network attack vector

Sensitive configuration disclosure via unprotected CGI data

Published Mar 1, 2022 · Updated Aug 4, 2024

Cleartext storage in Zyxel VMG3625-T50B firmware V5.50(ABTL.0)b2k allows remote authenticated users to read sensitive configuration data. A CGI program fails to protect the device's login-privilege and TR-069 configuration, exposing stored values through the management interface. Access requires successful authentication to that interface, and the TR-069 path is not exposed in generic firmware unless TR-069 is enabled.

CVSS severity6.5
Medium
EPSS probability0.49%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cleartext storage in Zyxel VMG3625-T50B firmware V5.50(ABTL.0)b2k allows remote authenticated users to read sensitive configuration data. A CGI program fails to protect the device's login-privilege and TR-069 configuration, exposing stored values through the management interface. Access requires successful authentication to that interface, and the TR-069 path is not exposed in generic firmware unless TR-069 is enabled.

The record

CVE
CVE-2021-35036
Published
Mar 1, 2022
Updated
Aug 4, 2024
Vendor
Zyxel Networks
Product
VMG3625-T50B Firmware
Classifications
CWE-312, T1552.001
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 1, 2022CVE 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=V5.50(ABTL.0)b2k

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Zyxel Networks · VMG3625-T50B Firmwareversion=V5.50(ABTL.0)b2k

Published CVSS scores

6.5Zyxel CorporationCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
3.5NIST NVDAV:N/AC:M/Au:S/C:P/I:N/A:N

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

Weakness, pattern, technique

CWE-312Cleartext Storage of Sensitive Information
T1552.001Unsecured Credentials: Credentials In Files

Public exploit references

No public exploit references are available in this record.

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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