CVE-2026-48558: SimpleHelp Authentication Bypass Vulnerability
- Is it exploited?
Yes. CISA added it to the Known Exploited Vulnerabilities catalog on , 17 days after the CVE record was published.
- How likely is exploitation in the next 30 days?
- 77.7%
EPSS score, percentile 99.6 of all scored records
- How severe?
- 9.5 Critical
CVSS v4.0 base score, given by the CNA
- What should I do?
CISA deadline . Apply mitigations in accordance with vendor instructions … Full text
- Which versions are affected?
Affected
- from 5.5.0 to before 5.5.16
- from 6.0 to before 6.0 RC2
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of ; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of ; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.
What to do
Required action, set by CISA
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 due date for this action: .
Advisories and patches
Linked from CISA's catalog entry
- https://simple-help.com/security/simplehelp-security-update-2026-05
- https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk
- https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk
- https://nvd.nist.gov/vuln/detail/CVE-2026-48558
Affected products and versions
As listed in the CVE record.
| Status | Versions |
|---|---|
| Affected | from 5.5.0 to before 5.5.16 |
| Affected | from 6.0 to before 6.0 RC2 |
Versions not listed are: affected.
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.
About this vulnerability
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.
Summary: CISA's KEV catalog, as of .
- CISA added CVE-2026-48558 to its Known Exploited Vulnerabilities (KEV) catalog on 29 Jun 2026.
- CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
- The due date CISA sets for the required action is 2 Jul 2026.
- The CVE record was published on 12 Jun 2026, 17 days before it was added to KEV.
- The CVE record carries a CVSS v4.0 base score of 9.5 (Critical), given by its CNA.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 77.7% (percentile 99.6), as of 28 Oct 2026.
- CISA's SSVC assessment in the CVE record: exploitation active, automatable yes, technical impact total.
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of ; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of ; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of . About the data.
Description
SimpleHelp Authentication Bypass via Missing OIDC JWT Signature Verification
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.
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.
Weakness
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.
Timeline
| Date | Event |
|---|---|
| CVE record published | |
| Added to CISA KEV | |
| CISA due date for the required action | |
| CVE record last updated |
References
More exploited SimpleHelp vulnerabilities
- CVE-2024-57726: SimpleHelp Missing Authorization Vulnerability
- CVE-2024-57728: SimpleHelp Path Traversal Vulnerability
- CVE-2024-57727: SimpleHelp Path Traversal Vulnerability