SimpleHelp OpenID Connect Auth Bypass to RCE [CVE-2026-48558]

CVE-2026-48558 is an authentication bypass (CWE-347, improper verification of cryptographic signature) in the SimpleHelp remote access/support platform's OpenID Connect (OIDC) login flow, where submitted identity tokens are accepted without verifying their signature. It is triggered when OIDC authentication is configured: a remote, unauthenticated attacker can submit a forged token containing arbitrary identity claims and obtain a fully authenticated technician session, and in some configurations this also bypasses multi-factor authentication. Related reporting describes a path from this bypass to remote code execution. Only SimpleHelp deployments using OIDC-based (e.g., SSO) authentication are affected; deployments relying on local SimpleHelp accounts are not described as affected. The flaw was added to CISA's Known Exploited Vulnerabilities catalog on 2026-06-29, confirming exploitation in the wild, with a 30% EPSS probability of exploitation within 30 days and no public proof-of-concept known.

Do: Update SimpleHelp to the latest release per vendor instructions, prioritizing any internet-facing server (CISA KEV listing means federal agencies must act under BOD 26-04). Until patched, restrict access to the SimpleHelp web login to trusted management networks (VPN/firewall) or temporarily switch from OIDC to local-account authentication with MFA. Verify whether OIDC is enabled on each instance and review technician login logs for sessions created with unusual or unexpected identity claims.