CVE-2026-48558
SimpleHelp Authentication Bypass Vulnerability
SimpleHelp SimpleHelp
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 status
CISA Known Exploited Vulnerabilities
Listed by CISA on 29 June 2026. US federal agencies were required to remediate it by 2 July 2026.
EPSS — exploitation probability
FIRST puts the probability of exploitation activity in the next 30 days at 11.5%, which is higher than 95.6% of all scored vulnerabilities. EPSS is a forecast of activity, not a measure of severity, and it is rescored daily.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Frequently asked questions
Is CVE-2026-48558 being exploited by ransomware groups?
No ransomware group in this database is currently recorded as exploiting CVE-2026-48558.
What does CVE-2026-48558 affect?
CVE-2026-48558 affects SimpleHelp SimpleHelp. 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.
How severe is CVE-2026-48558?
CVE-2026-48558 is rated CRITICAL with a CVSS base score of 10. EPSS puts the probability of exploitation in the next 30 days at 11.5%, higher than 95.6% of all scored vulnerabilities. It is listed in the CISA Known Exploited Vulnerabilities catalog, with a federal remediation deadline of 2 July 2026.
How should organisations respond to CVE-2026-48558?
Apply the vendor patch for SimpleHelp SimpleHelp as the first priority, and treat any internet-facing instance as the most urgent. Because this vulnerability is associated with ransomware activity, also review whether the affected systems were reachable before patching, rather than assuming that patching alone closes the incident.