CVE-2026-48558: SimpleHelp Authentication Bypass Vulnerability

What it is

SimpleHelp versions 5.5.15 and prior and 6.0 pre-release versions contain an authentication bypass vulnerability in the OIDC authentication flow. When OIDC authentication is configured, identity tokens submitted during login are accepted without verifying their cryptographic signature. In a vulnerable configuration, a remote, unauthenticated attacker can submit a forged token containing arbitrary identity claims to obtain a fully authenticated technician session. In some configurations, this may also allow bypass of multi-factor authentication. No user interaction is required.

Exploitation evidence

First exploit evidence seen: 2026-06-12 (earliest date across the sources below).

Exploited in the wild

• CISA KEV: listed since 2026-06-29. Source

Public exploit code

Metasploit

• exploit/multi/http/simplehelp_oidc_auth_bypass_rce: SimpleHelp OIDC Authentication Bypass Remote Code Execution (disclosure 2026-06-12)

GitHub proof-of-concept repositories below quality bar

1 public repositories from 1 accounts, first seen 2026-07-02.

Verify before running: public PoCs can be malicious. Read the code and only run it in an isolated lab. A PoC means exploit code is public, not that this CVE is exploited in the wild.

Sources: CISA KEV · Rapid7 Metasploit Framework module metadata · nomi-sec/PoC-in-GitHub.

How to fix it

CISA required action

Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines. (source: CISA KEV)

Fixed versions

• simple-help simplehelp: upgrade to 5.5.16 or later

Derived from the NVD CPE configuration (versionEndExcluding / versionEndIncluding). Always confirm with the vendor advisory.

Vendor advisories and patches

• https://simple-help.com/security/simplehelp-security-update-2026-05 (CISA KEV notes)
• https://simple-help.com/release-news (Release Notes)

MITRE ATT&CK mitigations for this chain

• M1027 Password Policies (for T1078) : Applications and appliances that utilize default username and password should be changed immediately after the installation, and before deployment to a production environment. When possible, applications that use SSH keys should be updated periodically and properly secured. Policies should minimize (if not eliminate)
• M1018 User Account Management (for T1078) : Regularly audit user accounts for activity and deactivate or remove any that are no longer needed.
• M1026 Privileged Account Management (for T1078, T1553) : Audit domain and local accounts as well as their permission levels routinely to look for situations that could allow an adversary to gain wide access by obtaining credentials of a privileged account. These audits should also include if default accounts have been enabled, or if new local accounts are created that have
• M1032 Multi-factor Authentication (for T1078) : Implement multi-factor authentication (MFA) across all account types, including default, local, domain, and cloud accounts, to prevent unauthorized access, even if credentials are compromised. MFA provides a critical layer of security by requiring multiple forms of verification beyond just a password. This measure sign
• M1013 Application Developer Guidance (for T1078) : Ensure that applications do not store sensitive data or credentials insecurely. (e.g. plaintext credentials in code, published credentials in repositories, or credentials in public cloud storage).
• M1017 User Training (for T1078) : Applications may send push notifications to verify a login as a form of multi-factor authentication (MFA). Train users to only accept valid push notifications and to report suspicious push notifications.
• M1015 Active Directory Configuration (for T1078) : Disable legacy authentication, which does not support MFA, and require the use of modern authentication protocols instead.
• M1036 Account Use Policies (for T1078) : Use conditional access policies to block logins from non-compliant devices or from outside defined organization IP ranges.
• M1038 Execution Prevention (for T1553) : System settings can prevent applications from running that haven't been downloaded through the Apple Store (or other legitimate repositories) which can help mitigate some of these issues. Also enable application control solutions such as AppLocker and/or Device Guard to block the loading of malicious content.
• M1028 Operating System Configuration (for T1553) : Windows Group Policy can be used to manage root certificates and the <code>Flags</code> value of <code>HKLM\\SOFTWARE\\Policies\\Microsoft\\SystemCertificates\\Root\\ProtectedRoots</code> can be set to 1 to prevent non-administrator users from making further root installations into their own HKCU certificate store.

Detection Generic guidance

• Initial Access: Alert on unusual requests to the affected service (odd paths, oversized payloads, exploit strings) in WAF, reverse-proxy and application logs.
• Persistence: Look for new files in web roots, new scheduled tasks/services, and new accounts created after the exposure window.
• Privilege Escalation: Alert on processes gaining SYSTEM/root unexpectedly, and on exploitation crashes of privileged services.

Response checklist Generic guidance

1. Inventory: find every instance of the affected product and version (include internet-facing and forgotten ones).
2. Patch or mitigate per the vendor advisory; if you cannot patch, remove internet exposure or apply the vendor workaround.
3. Assume compromise if the system was exposed before patching: hunt for the indicators in the advisory and review logs back to the disclosure date.
4. Rotate credentials and secrets stored on or used by the affected system if compromise cannot be ruled out.