CyberSecBulletin
CVE-2026-48558Exploited in the wildNVD status: Analyzed

SimpleHelp Authentication Bypass

Published Updated By the CyberSecBulletin desk

CVE-2026-48558 is a critical-severity improper verification of cryptographic signature vulnerability in SimpleHelp, with a CVSS 3.1 base score of 10.0 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 5.5.16, 6.0 RC2 as the first without the flaw, so updating SimpleHelp to one of those releases or later removes the exposure. CISA added it to the Known Exploited Vulnerabilities catalogue on June 29, 2026, which means attacks have been observed in the wild.

Patch now

Attackers are already exploiting this vulnerability, according to CISA.

What to do

  1. Update SimpleHelp to 5.5.16 or 6.0 RC2, whichever matches your release line, or a later version.
  2. CISA's 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.
  3. Read the advisory on simple-help.com for workarounds and exact fixed builds.
  4. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
SimpleHelpSimpleHelp5.5.0 up to, but not including, 5.5.16; 6.0 up to, but not including, 6.0 RC25.5.16, 6.0 RC2

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
ChangedThe attack can reach beyond the vulnerable component into other systems.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H. Scored by CNA (vulncheck.com).

Scoring systemScoreSeverityScored by
CVSS 4.09.5CriticalCNA (vulncheck.com)
CVSS 3.110.0CriticalCNA (vulncheck.com)

Official 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.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Verification of Cryptographic Signature

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

More Improper Verification of Cryptographic Signature vulnerabilities (CWE-347)

Timeline

  1. CVE record published.
  2. Added to CISA's Known Exploited Vulnerabilities catalogue.
  3. CISA published its SSVC assessment (exploitation: active, automatable: yes, technical impact: total).
  4. Deadline for US federal agencies to remediate, set by CISA.
  5. Record last changed materially (score, affected products, status or references).

References

Patches and release notes

Recent Improper Verification of Cryptographic Signature vulnerabilities

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