CVE-2026-48558: SimpleHelp Authentication Bypass Vulnerability

In short

SimpleHelp SimpleHelp has a weakness classified as improper verification of cryptographic signature (CWE-347). CISA added it to its Known Exploited Vulnerabilities catalog on 2026-06-29. NVD lists CVSS 4.0 at 9.5 CRITICAL.

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.” — CISA KEV, retrieved 2026-11-01

“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.” — NVD, retrieved 2026-11-01

Who is affected

SimpleHelp SimpleHelp. NVD lists the following versions as affected:

• Versions before 5.5.16
• Versions version 6.0

Exploitation status

CISA KEV added: 2026-06-29. Known ransomware campaign use: Not reported by CISA. Due date CISA set for US federal civilian agencies: 2026-07-02.

Scores

NVD CVSS 4.0: 9.5 CRITICAL; vector 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X; source [email protected].

EPSS by FIRST: 77.66%; percentile 99.56; score date 2026-10-31. EPSS estimates the probability of exploitation in the next 30 days.

CWE: CWE-347.

Timeline

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 KEV

What to do

• Confirm whether you run SimpleHelp SimpleHelp and which version.
• Apply the vendor update or mitigation in the advisory.
• Follow CISA’s required action.
• Review the vendor guidance on signs of compromise.
• Track the fix through completion.

References

• Third Party Advisory: https://horizon3.ai/attack-research/disclosures/cve-2026-48558-simplehelp-authentication-bypass-iocs/
• Release Notes: https://simple-help.com/release-news
• Patch, Vendor Advisory: https://simple-help.com/security/simplehelp-security-update-2026-05
• Technical Description, Third Party Advisory: https://blackpointcyber.com/blog/a-djinn-in-the-machine-taskweavers-node-js-intrusion-chain/
• NVD detail
• CVE.org record
• CISA KEV catalog

Sources and dates

CISA Known Exploited Vulnerabilities Catalog, version 2026.10.30; retrieved 2026-11-01. CISA KEV data: CC0 1.0. No endorsement by CISA.

NVD retrieved: 2026-11-01. This product uses the NVD API but is not endorsed or certified by the NVD.

EPSS scores by FIRST; score date 2026-10-31.