Authentication Bypass

auth CRITICAL

Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.

How It Works

Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications. Instead of cracking passwords through brute force, attackers manipulate the authentication process itself to gain unauthorized entry. This typically occurs through one of several pathways: exploiting hardcoded credentials embedded in source code or configuration files, manipulating parameters in authentication requests to skip verification steps, or leveraging broken session management that fails to properly validate user identity.

The attack flow often begins with reconnaissance to identify authentication endpoints and their underlying logic. Attackers may probe for default administrative credentials that were never changed, test whether certain URL paths bypass login requirements entirely, or intercept and modify authentication tokens to escalate privileges. In multi-step authentication processes, flaws in state management can allow attackers to complete only partial verification steps while still gaining full access.

More sophisticated variants exploit single sign-on (SSO) or OAuth implementations where misconfigurations in trust relationships allow attackers to forge authentication assertions. Parameter tampering—such as changing a "role=user" field to "role=admin" in a request—can trick poorly designed systems into granting elevated access without proper verification.

Impact

Complete account takeover — attackers gain full control of user accounts, including administrative accounts, without knowing legitimate credentials
Unauthorized data access — ability to view, modify, or exfiltrate sensitive information including customer data, financial records, and intellectual property
System-wide compromise — admin-level access enables installation of backdoors, modification of security controls, and complete infrastructure takeover
Lateral movement — bypassed authentication provides a foothold for moving deeper into networks and accessing additional systems
Compliance violations — unauthorized access triggers breach notification requirements and regulatory penalties

Real-World Examples

CrushFTP suffered a critical authentication bypass allowing attackers to access file-sharing functionality without any credentials. The vulnerability enabled direct server-side template injection, leading to remote code execution on affected systems. Attackers actively exploited this in the wild to establish persistent access to enterprise file servers.

Palo Alto's Expedition migration tool contained a flaw permitting attackers to reset administrative credentials without authentication. This allowed complete takeover of the migration environment, potentially exposing network configurations and security policies being transferred between systems.

SolarWinds Web Help Desk (CVE-2024-28987) shipped with hardcoded internal credentials that could not be changed through normal administrative functions. Attackers discovering these credentials gained full administrative access to helpdesk systems containing sensitive organizational information and user data.

Mitigation

Implement multi-factor authentication (MFA) — requires attackers to compromise additional verification factors beyond bypassed primary authentication
Eliminate hardcoded credentials — use secure credential management systems and rotate all default credentials during deployment
Enforce authentication on all endpoints — verify every request requires valid authentication; no "hidden" administrative paths should exist
Implement proper session management — use cryptographically secure session tokens, validate on server-side, enforce timeout policies
Apply principle of least privilege — limit damage by ensuring even authenticated users only access necessary resources
Regular security testing — conduct penetration testing specifically targeting authentication logic and flows

Recent CVEs (37807)

CVE-2021-32951

EPSS 1% CVSS 5.3

MEDIUM PATCH This Month

WebAccess/NMS (Versions prior to v3.0.3_Build6299) has an improper authentication vulnerability, which may allow unauthorized users to view resources monitored and controlled by the WebAccess/NMS, as. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity.

Authentication Bypass Webaccess Nms Advantech

NVD

CVE-2021-41157

EPSS 2% CVSS 5.3

MEDIUM POC PATCH This Month

FreeSWITCH is a Software Defined Telecom Stack enabling the digital transformation from proprietary telecom switches to a software implementation that runs on any commodity hardware. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.

Authentication Bypass Freeswitch

NVD GitHub

CVE-2021-41873

EPSS 1% CVSS 10.0

CRITICAL Act Now

Penguin Aurora TV Box 41502 is a high-end network HD set-top box produced by Tencent Video and Skyworth Digital. Rated critical severity (CVSS 10.0), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Authentication Bypass Penguin Aurora Box Firmware Skyworth

NVD

CVE-2021-41308

EPSS 1% CVSS 6.5

MEDIUM PATCH This Month

Affected versions of Atlassian Jira Server and Data Center allow authenticated yet non-administrator remote attackers to edit the File Replication settings via a Broken Access Control vulnerability. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity.

Authentication Bypass Jira Atlassian +3

NVD

CVE-2021-41307

EPSS 2% CVSS 7.5

HIGH PATCH This Week

Affected versions of Atlassian Jira Server and Data Center allow unauthenticated remote attackers to view the names of private projects and private filters via an Insecure Direct Object References. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.

Authentication Bypass Jira Atlassian +2

NVD

CVE-2021-41306

EPSS 2% CVSS 7.5

HIGH PATCH This Week

Affected versions of Atlassian Jira Server and Data Center allow anonymous remote attackers to view private project and filter names via an Insecure Direct Object References (IDOR) vulnerability in. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.

Authentication Bypass Jira Atlassian +2

NVD

CVE-2021-41305

EPSS 1% CVSS 7.5

HIGH PATCH This Week

Affected versions of Atlassian Jira Server and Data Center allow anonymous remote attackers to view the names of private projects and filters via an Insecure Direct Object References (IDOR). Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.

Authentication Bypass Jira Atlassian +1

NVD

CVE-2021-39225

EPSS 1% CVSS 8.1

HIGH PATCH This Week

Nextcloud is an open-source, self-hosted productivity platform. Rated high severity (CVSS 8.1), this vulnerability is remotely exploitable, low attack complexity.

Authentication Bypass Deck Nextcloud

NVD GitHub

CVE-2021-34864

EPSS 0% CVSS 8.8

HIGH This Week

This vulnerability allows local attackers to escalate privileges on affected installations of Parallels Desktop 16.1.3 (49160). Rated high severity (CVSS 8.8), this vulnerability is low attack complexity. No vendor patch available.

Authentication Bypass RCE Parallels Desktop +1

NVD

CVE-2021-37624

EPSS 4% CVSS 7.5

HIGH POC This Week

FreeSWITCH is a Software Defined Telecom Stack enabling the digital transformation from proprietary telecom switches to a software implementation that runs on any commodity hardware. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.

Authentication Bypass Freeswitch

NVD GitHub

CVE-2021-24779

EPSS 1% CVSS 6.5

MEDIUM POC This Month

The WP Debugging WordPress plugin before 2.11.0 has its update_settings() function hooked to admin_init and is missing any authorisation and CSRF checks, as a result, the settings can be updated by. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.

WordPress Authentication Bypass CSRF +1

NVD WPScan

CVE-2021-21703

EPSS 1% CVSS 7.0

HIGH POC PATCH This Week

In PHP versions 7.3.x up to and including 7.3.31, 7.4.x below 7.4.25 and 8.0.x below 8.0.12, when running PHP FPM SAPI with main FPM daemon process running as root and child worker processes running. Rated high severity (CVSS 7.0). Public exploit code available.

PHP Authentication Bypass Debian +7

NVD

CVE-2021-41171

EPSS 2% CVSS 8.8

HIGH POC PATCH This Week

eLabFTW is an open source electronic lab notebook manager for research teams. Rated high severity (CVSS 8.8), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available.

Authentication Bypass Elabftw

NVD GitHub Exploit-DB

CVE-2021-42539

EPSS 1% CVSS 8.8

HIGH PATCH This Week

The affected product is vulnerable to a missing permission validation on system backup restore, which could lead to account take over and unapproved settings change. Rated high severity (CVSS 8.8), this vulnerability is remotely exploitable, low attack complexity. This Missing Authentication for Critical Function vulnerability could allow attackers to access critical functionality without authentication.

Authentication Bypass Wireless 1420 Gateway Firmware Wireless 1410 Gateway Firmware +2

NVD

CVE-2021-0706

EPSS 0% CVSS 5.5

MEDIUM This Month

In startListening of PluginManagerImpl.java, there is a possible way to disable arbitrary app components due to a missing permission check. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. No vendor patch available.

Authentication Bypass Denial Of Service Google +1

NVD

CVE-2021-0643

EPSS 0% CVSS 5.5

MEDIUM This Month

In getAllSubInfoList of SubscriptionController.java, there is a possible way to retrieve a long term identifier without the correct permissions due to a missing permission check. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. No vendor patch available.

Authentication Bypass Information Disclosure Google +1

NVD

CVE-2021-38457

EPSS 1% CVSS 9.8

CRITICAL PATCH Act Now

The server permits communication without any authentication procedure, allowing the attacker to initiate a session with the server without providing any form of authentication. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity.

Authentication Bypass Versiondog Auvesy

NVD

CVE-2021-36357

EPSS 1% CVSS 9.8

CRITICAL PATCH Act Now

An issue was discovered in OpenPOWER 2.6 firmware. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity.

Authentication Bypass Skiboot

NVD GitHub

CVE-2021-42299

EPSS 1% CVSS 5.6

MEDIUM PATCH This Month

Microsoft Surface Pro 3 Security Feature Bypass Vulnerability. Rated medium severity (CVSS 5.6).

Authentication Bypass Microsoft Surface Pro 3 Firmware

NVD

CVE-2021-42762

EPSS 1% CVSS 5.3

MEDIUM POC This Month

BubblewrapLauncher.cpp in WebKitGTK and WPE WebKit before 2.34.1 allows a limited sandbox bypass that allows a sandboxed process to trick host processes into thinking the sandboxed process is not. Rated medium severity (CVSS 5.3), this vulnerability is low attack complexity. Public exploit code available and no vendor patch available.

Authentication Bypass Apple Debian +6

NVD GitHub

CVE-2021-21745

EPSS 56% CVSS 4.3

MEDIUM POC THREAT This Month

ZTE MF971R product has a Referer authentication bypass vulnerability. Rated medium severity (CVSS 4.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Authentication Bypass CSRF Zte +1

NVD

CVE-2021-35666

EPSS 1% CVSS 5.9

MEDIUM PATCH This Month

Vulnerability in the Oracle HTTP Server product of Oracle Fusion Middleware (component: OSSL Module). Rated medium severity (CVSS 5.9), this vulnerability is remotely exploitable, no authentication required.

Authentication Bypass Oracle Http Server

NVD

CVE-2021-35665

EPSS 1% CVSS 6.1

MEDIUM PATCH This Month

Vulnerability in the Hyperion Financial Reporting product of Oracle Hyperion (component: Repository). Rated medium severity (CVSS 6.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity.

Authentication Bypass Oracle Hyperion Financial Reporting

NVD

CVE-2021-35655

EPSS 1% CVSS 5.3

MEDIUM PATCH This Month

Vulnerability in the Essbase Administration Services product of Oracle Essbase (component: EAS Console). Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity.

Authentication Bypass Oracle Essbase Administration Services

NVD

CVE-2021-35653

EPSS 1% CVSS 7.7

HIGH PATCH This Week

Vulnerability in the Essbase Administration Services product of Oracle Essbase (component: EAS Console). Rated high severity (CVSS 7.7), this vulnerability is remotely exploitable, low attack complexity.

Authentication Bypass Oracle Essbase Administration Services

NVD

CVE-2021-35651

EPSS 1% CVSS 8.5

HIGH PATCH This Week

Vulnerability in the Essbase Administration Services product of Oracle Essbase (component: EAS Console). Rated high severity (CVSS 8.5), this vulnerability is remotely exploitable, low attack complexity.

Authentication Bypass Oracle Essbase Administration Services

NVD

CVE-2021-35640

EPSS 1% CVSS 2.7

LOW Monitor

Vulnerability in the MySQL Server product of Oracle MySQL (component: Server: DDL). Rated low severity (CVSS 2.7), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.