How broadly exploitable is this WebAuthn vulnerability?

Exploitability depends on an attacker's ability to capture a valid WebAuthn assertion, but once obtained, that assertion can typically be replayed multiple times because the server does not enforce challenge freshness or single-use behavior.

What level of access does an attacker need to exploit this issue?

The attacker must gain access to at least one valid WebAuthn assertion and its associated data, which might occur via cross-site scripting in the application, interception of traffic in a weakly protected network path, or accidental logging of assertions in plaintext. In many practical scenarios, the attacker will also need or obtain the user's primary credentials or session to fully leverage the replay.

What is the safest general fix pattern for developers?

Implement a standards-compliant WebAuthn flow where challenges are generated and stored on the server, bound to a specific session or login attempt, and invalidated after a single verification. Verification logic should compare the authenticator's response to the server-stored challenge and enforce replay protection via single-use semantics and, when applicable, sign counter checks.

Severity:

HIGH RISK

(8.2)

Improper WebAuthn Authentication (CWE-287) in OneUptime 2FA Flow

CVE-2026-28787

Published:

Mar 5, 2026

Status:

Received

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-78

CRITICAL RISK

CRITICAL

(9.9)

Command Injection in MCP Stdio Configuration Validation (CWE-78) in WeKnora

Remote Code Execution

March 7, 2026

CWE-89

CRITICAL RISK

CRITICAL

(9.9)

SQL Injection via PostgreSQL Array/Row Expressions (CWE-89) in WeKnora Query Engine

Remote Code Execution via SQL Injection on the Database Server

March 7, 2026

Vulnerability Type

Category:

Authentication Bypass

CWE:

CWE-287;CWE-294

Impact:

Second-Factor Authentication Bypass and Account Compromise

Severity:

HIGH RISK

(8.2)

CVSS Version:

3.1

Vulnerability Type

Category:

Authentication Bypass

CWE:

CWE-287;CWE-294

Impact:

Second-Factor Authentication Bypass and Account Compromise

Severity:

HIGH RISK

(8.2)

CVSS Version:

3.1

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355 Bryant St. San Francisco, CA 94107, USA

Ask AI for summary of CodeAnt

Improper WebAuthn Authentication (CWE-287) in OneUptime 2FA Flow

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

CRITICAL RISK

CRITICAL

(9.9)

Command Injection in MCP Stdio Configuration Validation (CWE-78) in WeKnora

CRITICAL RISK

CRITICAL

(9.9)

SQL Injection via PostgreSQL Array/Row Expressions (CWE-89) in WeKnora Query Engine

Vulnerability Type

Vulnerability Type

Vulnerability Type

Catch This CVE While Code Is Being Written

Ship clean & secure code faster

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