How broadly exploitable is this vulnerability?

It is broadly exploitable wherever the ZimaOS login interface is reachable. An attacker who can access the management or web UI and knows an affected service username can usually obtain authenticated access without the true password.

Does an attacker need valid credentials or prior access?

No valid password is required. The attacker only needs network or local access to the login interface and knowledge or guesswork of one of the special usernames that trigger the flawed authentication path.

What is the safest general fix pattern?

The safest approach is to unify and harden the authentication logic so that every account type requires a successful password (or strong alternative factor) check before session creation, and to remove any special-case branches that bypass or override password verification.

Severity:

CRITICAL RISK

(9.4)

Improper Authentication Bypass (CWE-287) in ZimaOS Service Account Login

CVE-2026-21891

Published:

Jan 8, 2026

Status:

Analyzed

Summary

Affected Context

Exploit Preconditions

Why This Happens

Potential Impact

General Mitigation Guidance

How Teams Detect Issues Like This

Frequently Asked Questions

Source

NDV

Recent Vulnerabilities

CWE-77;CWE-78

HIGH RISK

HIGH

(7.3)

OS Command Injection (CWE-78) in Totolink A7100RU setGameSpeedCfg CGI Handler

Remote Code Execution on the Router

April 6, 2026

CWE-77;CWE-78

HIGH RISK

HIGH

(7.3)

OS Command Injection (CWE-78) in Totolink A7100RU setFirewallType Handler

Remote Code Execution on Router Firmware

April 6, 2026

Vulnerability Type

Category:

Improper Authentication

CWE:

CWE-287

Impact:

Authentication Bypass and Unauthorized Account Access

Severity:

CRITICAL RISK

(9.4)

CVSS Version:

3.1

Vulnerability Type

Category:

Improper Authentication

CWE:

CWE-287

Impact:

Authentication Bypass and Unauthorized Account Access

Severity:

CRITICAL RISK

(9.4)

CVSS Version:

3.1

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355 Bryant St. San Francisco, CA 94107, USA

Ask AI for summary of CodeAnt

Improper Authentication Bypass (CWE-287) in ZimaOS Service Account Login

Summary

Affected Context

Exploit Preconditions

Why This Happens

Potential Impact

General Mitigation Guidance

How Teams Detect Issues Like This

Frequently Asked Questions

Source

Recent Vulnerabilities

HIGH RISK

HIGH

(7.3)

OS Command Injection (CWE-78) in Totolink A7100RU setGameSpeedCfg CGI Handler

HIGH RISK

HIGH

(7.3)

OS Command Injection (CWE-78) in Totolink A7100RU setFirewallType Handler

Vulnerability Type

Vulnerability Type

Vulnerability Type

Catch This CVE While Code Is Being Written

Ship clean & secure code faster

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