Security Digest · Vulnerability record · Known exploited
CVE-2026-48558: SimpleHelp Authentication Bypass Vulnerability
Exploited in the wild (CISA KEV). SimpleHelp versions 5.5.15 and prior and 6.0 pre-release versions contain an authentication bypass vulnerability in the OIDC authentication flow.
CISA KEV · added 2026-06-29 CVSS 9.5 Critical EPSS 5.7% · p93
Should you act?
Exploited: patch now if you run it
CISA has confirmed exploitation in the wild. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- Yes, if you run SimpleHelp SimpleHelp. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2026-06-29, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2026-07-02; treat that as the outer limit, not the target.
- EPSS 5.7%, percentile 93: FIRST’s model estimates a 5.7% chance of exploitation activity in the next 30 days, higher than 93% of all scored CVEs (elevated). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
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.
CISA’s summary
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.
Weakness type: CWE-347.
Product: SimpleHelp SimpleHelp · Assigned by: VulnCheck · Published: 2026-06-12
Affected and fixed versions
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| SimpleHelp | SimpleHelp | 5.5.0 < 5.5.16, 6.0 < 6.0 RC2 |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| VulnCheck | 4.0 | 9.5 Critical | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H |
| VulnCheck | 3.1 | 10 Critical | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H |
- Attack vector: network (remotely reachable)
- Attack complexity: low
- Attack requirements: present (depends on deployment conditions)
- Privileges required: none (no login)
- User interaction: none
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- CISA KEV: added 2026-06-29; federal due date 2026-07-02. Known ransomware use: Unknown.
- 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.
- CISA SSVC assessment: exploitation active, automatable yes, technical impact total.
- FIRST EPSS (model of 2026-10-21): 5.72% probability of exploitation activity in the next 30 days; percentile 93.
Timeline
- — CVE record published by VulnCheck
- — Added to CISA’s Known Exploited Vulnerabilities catalog
- — CISA remediation deadline for US federal agencies
- — CVE record last updated
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vendor and project advisories, patches
- simple-help.com simple-help.com
- simple-help.com simple-help.com
Vulnerability records
- CVE.org record CVE-2026-48558 cve.org
- NVD entry CVE-2026-48558 nvd.nist.gov
Government
- CISA Known Exploited Vulnerabilities catalog entry cisa.gov
- Listed in CISA KEV notes (cisa.gov) cisa.gov
- Listed in CISA KEV notes (cisa.gov) cisa.gov
Other references from the CVE record and advisory
- horizon3.ai horizon3.ai
- blackpointcyber.com blackpointcyber.com
All exploited SimpleHelp vulnerabilities · Today’s Security Digest