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CVE-2026-48558: SimpleHelp Authentication Bypass Vulnerability

CVE-2026-48558 is rated critical with a CVSS v3.1 base score of 10.0 and affects SimpleHelp SimpleHelp. Per its scoring, it can be exploited over the network, without authentication, without any user interaction. The scored impact on confidentiality, integrity and availability is the highest available. CISA added it to its Known Exploited Vulnerabilities catalog on 2026-06-29, which means exploitation in the wild has been observed.

Vulnerability description

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.

Severity breakdown

CVSS v3.1 10.0: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

• Attack vector: Network. Exploitable remotely over the network, with no need for local or physical access.
• Attack complexity: Low. No special conditions; the attack can be repeated reliably.
• Privileges required: None. No account or prior access is needed.
• User interaction: None. No action from any user is needed.
• Scope: Changed. Impact reaches beyond the vulnerable component to other resources.
• Confidentiality impact: High. Total loss of confidentiality; sensitive data can be fully disclosed.
• Integrity impact: High. Total loss of integrity; data or system state can be fully modified.
• Availability impact: High. Total loss of availability; the component can be shut down.

Underlying weakness

CWE-347: Improper Verification of Cryptographic Signature

The product does not verify, or incorrectly verifies, the cryptographic signature for data.

Affected products

• Simplehelp: before 5.5.16; 6.0 pre-release

References

• https://simple-help.com/security/simplehelp-security-update-2026-05
• https://horizon3.ai/attack-research/disclosures/cve-2026-48558-simplehelp-authentication-bypass-iocs/
• https://blackpointcyber.com/blog/a-djinn-in-the-machine-taskweavers-node-js-intrusion-chain/
• https://simple-help.com/release-news
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-48558