CVE-2026-40954: Absolute Secure Access DoS Vulnerability

CVE-2026-40954 Overview

CVE-2026-40954 is an integer underflow vulnerability [CWE-191] in the traffic parsing function of Absolute Secure Access clients prior to version 14.55. An attacker with intimate knowledge of and total control over the tunnel protocol can trigger a non-persistent denial of service (DoS) condition against their own client. The flaw affects the client-side tunnel processing logic and does not enable remote compromise of other users or the server infrastructure.

Critical Impact
A self-directed, non-persistent client DoS achievable only by an attacker who fully controls the tunnel protocol used by their own Absolute Secure Access client.

Affected Products

Absolute Secure Access clients prior to version 14.55
Deployments running the vulnerable traffic parsing component
Windows and mobile endpoints using Absolute Secure Access tunnels

Discovery Timeline

2026-07-15 - CVE-2026-40954 published to NVD
2026-07-16 - Last updated in NVD database

Technical Details for CVE-2026-40954

Vulnerability Analysis

The vulnerability resides in the traffic parsing function of the Absolute Secure Access client. During parsing of tunnel protocol messages, the client performs arithmetic on a length or offset field without properly validating the input. When a crafted value causes the calculation to wrap below zero, an integer underflow occurs and downstream logic operates on an invalid size. This state disrupts the client process and produces a non-persistent DoS. The condition clears once the client is restarted or the tunnel is re-established.

Exploitation requires the attacker to have full control over the tunnel protocol interaction with their own client. The impact is limited to availability of the local client and does not extend to confidentiality or integrity of tunnel data.

Root Cause

The root cause is missing or insufficient bounds validation before arithmetic on an untrusted numeric field within the tunnel parser. This maps to [CWE-191] Integer Underflow (Wrap or Wraparound). The parser trusts protocol-supplied length values and subtracts from them without checking that the result stays within the expected range.

Attack Vector

The attack vector is network-adjacent but self-directed. An actor who fully controls the tunnel protocol endpoint can send a malformed message that triggers the underflow inside their own Secure Access client. The attacker cannot leverage this flaw against other tenants, remote users, or the corporate gateway. Refer to the Absolute Security Advisory for vendor confirmation.

No verified public proof-of-concept code is available. The vulnerability is described in prose based on the vendor advisory.

Detection Methods for CVE-2026-40954

Indicators of Compromise

Unexpected termination or crash events of the Absolute Secure Access client process on endpoints
Repeated tunnel re-establishment attempts from a single client within a short window
Client-side logs showing malformed tunnel protocol frames prior to a crash

Detection Strategies

Monitor endpoint process telemetry for abnormal exits of the Secure Access client binary
Correlate client crash events with preceding tunnel protocol errors in Absolute Secure Access logs
Track Secure Access client version inventory to identify hosts running versions earlier than 14.55

Monitoring Recommendations

Ingest Absolute Secure Access client logs into a central log platform for crash pattern analysis
Alert on repeated client restarts within a defined interval on the same endpoint
Review connection metadata from Secure Access gateways for clients exhibiting instability

How to Mitigate CVE-2026-40954

Immediate Actions Required

Inventory all endpoints running Absolute Secure Access clients and identify versions prior to 14.55
Upgrade affected clients to version 14.55 or later as provided by Absolute
Restrict client installation and update permissions to authorized administrators

Patch Information

Absolute has released a fixed version of Secure Access that addresses the integer underflow in the traffic parsing function. Administrators should deploy version 14.55 or later. Full remediation details are available in the Absolute Security Advisory. The EPSS score is 0.201% as of 2026-07-16, indicating a low predicted likelihood of exploitation, but patching remains the authoritative remediation.

Workarounds

No vendor-supplied workaround is documented; upgrading to version 14.55 is the recommended path
Limit which users can configure or replace the tunnel protocol endpoint on managed devices
Restart the Secure Access client to recover from the non-persistent DoS state when it occurs

bash

# Example: query installed Absolute Secure Access client version on Windows
Get-ItemProperty "HKLM:\Software\Microsoft\Windows\CurrentVersion\Uninstall\*" |
  Where-Object { $_.DisplayName -like "*Absolute Secure Access*" } |
  Select-Object DisplayName, DisplayVersion