CVE-2026-46749: SINEC INS Auth Bypass Vulnerability

CVE-2026-46749 Overview

CVE-2026-46749 affects Siemens SINEC INS in all versions prior to V1.0 SP2 Update 6. The application implements password hashing with a static, hardcoded salt shared across every user and installation. The implementation also uses an insufficient number of hashing iterations. An attacker with access to stored password hashes can recover plaintext credentials through brute-force or precomputed dictionary attacks. Successful credential recovery leads to unauthorized access to the SINEC INS infrastructure services platform.

Critical Impact
Recovered SINEC INS credentials can grant attackers unauthorized access to industrial network infrastructure services, enabling lateral movement within operational technology environments.

Affected Products

Siemens SINEC INS — All versions prior to V1.0 SP2 Update 6

Discovery Timeline

2026-06-09 - CVE-2026-46749 published to the National Vulnerability Database
2026-06-09 - Last updated in NVD database

Technical Details for CVE-2026-46749

Vulnerability Analysis

The vulnerability is classified under [CWE-760] (Use of a One-Way Hash with a Predictable Salt). Siemens SINEC INS stores user passwords using a hashing scheme that combines two cryptographic weaknesses. First, the salt value is hardcoded into the application and reused for every user account across all installations. Second, the iteration count for the key derivation function is set too low to provide adequate computational resistance.

A static salt eliminates the primary defense against precomputed attacks. An attacker who builds a rainbow table for the shared salt can test the same table against every SINEC INS deployment worldwide. The low iteration count further reduces the cost of online brute-force attempts against individual hashes.

Exploitation requires Local access with High privileges, which constrains the attack surface. However, any user who obtains read access to the credential store, through configuration backups, database exports, or local file disclosure, can begin offline cracking immediately.

Root Cause

The root cause is the developer's reliance on a constant salt value embedded in source code, combined with a misconfigured work factor in the password-based key derivation function. Per-user random salts and a calibrated iteration count are standard requirements for secure password storage.

Attack Vector

An attacker with local, high-privileged access exfiltrates the password hash database from a SINEC INS installation. The attacker then performs offline cracking using precomputed tables generated for the known static salt. Recovered credentials are reused to authenticate to the same or other SINEC INS deployments. See the Siemens Security Advisory SSA-860189 for vendor-confirmed technical details.

Detection Methods for CVE-2026-46749

Indicators of Compromise

Unexpected read access to SINEC INS credential storage files or database tables containing user hashes.
Authentication events for SINEC INS accounts originating from previously unseen hosts or IP ranges.
Configuration backups or database exports transferred off the SINEC INS host outside scheduled maintenance windows.

Detection Strategies

Audit file access on SINEC INS hosts for processes reading the user credential store outside the application's own service account.
Correlate successful SINEC INS logins with prior file access events on the credential database to identify offline-cracking patterns.
Monitor for high-privilege local sessions on SINEC INS systems that perform bulk data export operations.

Monitoring Recommendations

Forward SINEC INS authentication logs to a centralized SIEM for anomaly analysis on login source, time, and frequency.
Establish baselines for administrative access to SINEC INS and alert on deviations.
Track integrity of password storage files using file integrity monitoring on the SINEC INS host.

How to Mitigate CVE-2026-46749

Immediate Actions Required

Update SINEC INS to V1.0 SP2 Update 6 or later, which addresses the hashing weakness.
Force a password reset for all SINEC INS user accounts after applying the update so new hashes use the corrected scheme.
Restrict local administrative access on SINEC INS hosts to a minimal set of named operators.

Patch Information

Siemens has released SINEC INS V1.0 SP2 Update 6 to remediate CVE-2026-46749. Administrators should apply the update following the guidance in the Siemens Security Advisory SSA-860189.

Workarounds

Limit access to the SINEC INS server to trusted operators and segregate it on a dedicated management network until the patch is applied.
Enforce strong, high-entropy passwords for all SINEC INS accounts to increase the cost of offline brute-force attempts.
Protect configuration backups and database exports with strong encryption and restricted storage locations.

bash

# Configuration example
# Verify installed SINEC INS version and confirm update to V1.0 SP2 Update 6
# Refer to Siemens SSA-860189 for vendor-provided update procedures