CVE-2026-48558: SimpleHelp Authentication Bypass Vulnerability
What it is
SimpleHelp contains 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.
What to do
Treat this as urgent. Identify every affected system, starting with anything internet-facing, and apply the vendor fix or mitigation within days. If you cannot patch quickly, isolate or disable the affected service and watch for signs of compromise.
- Priority
- Act now: Patch or mitigate internet-facing systems within days.
- Severity (CVSS)
- 9.5 critical
- CISA assessment (SSVC)
- actively exploited; attackers can automate it at scale; total control of the affected system
- Exploit probability (EPSS, 30 days)
- 5.7%, higher than 92% of all CVEs
- Added to CISA KEV
- 29 June 2026
- CISA fix-by date
- 2 July 2026 (US federal agencies; a sensible deadline for everyone)
- Ransomware use
- Not known
- Weakness
- CWE-347
References
- NIST NVD entry
- CISA KEV entry
- horizon3.ai/attack-research/disclosures/cve-2026-48558-simplehelp-authentication
- simple-help.com/release-news
- simple-help.com/security/simplehelp-security-update-2026-05
- blackpointcyber.com/blog/a-djinn-in-the-machine-taskweavers-node-js-intrusion-ch
- www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-48558
Sources: CISA Known Exploited Vulnerabilities · FIRST Exploit Prediction Scoring System (EPSS) · NIST National Vulnerability Database · CISA Vulnrichment (SSVC), via the CVE Program. This product uses data from the NVD API but is not endorsed or certified by the NVD. Summaries are machine-written from CISA’s description; treat the vendor’s advisory as the authority for fixes.