CVE-2026-25607: STER Software Weak Password Encoding Flaw

CVE-2026-25607 Overview

CVE-2026-25607 is a weak cryptography vulnerability affecting STER software. The flaw resides in the password encoding algorithm used by the application. An attacker with local access can analyze how known password values are encoded and reverse-engineer the algorithm to recover the values of other stored passwords. The issue is tracked under CWE-261: Weak Encoding for Password. The vendor addressed the vulnerability in version 9.5 of STER software.

Critical Impact

A local attacker with low privileges can recover plaintext passwords by analyzing the deterministic, reversible encoding scheme used to store credentials in STER software.

Affected Products

• STER software versions prior to 9.5
• STER software (fixed in version 9.5)
• Vendor information not specified in NVD entry

Discovery Timeline

• 2026-05-22 - CVE-2026-25607 published to NVD
• 2026-05-22 - Last updated in NVD database

Technical Details for CVE-2026-25607

Vulnerability Analysis

The vulnerability stems from the use of a weak password encoding algorithm rather than a cryptographically secure password hashing function. STER software encodes stored passwords using a reversible transformation. An attacker who can observe encoded output for chosen or known plaintext inputs can derive the encoding scheme. Once the scheme is reconstructed, any encoded password value held by the application can be decoded to its original plaintext form. The defect is classified under CWE-261, which covers weak encoding applied to passwords. Secure systems require one-way password hashing with a per-credential salt and a memory-hard or iterated function such as Argon2, scrypt, or bcrypt. Encoding schemes, by contrast, are reversible by design and do not provide confidentiality against an attacker who can study their behavior.

Root Cause

The root cause is the selection of a reversible encoding routine to protect stored passwords. The algorithm produces deterministic outputs without a secret key, salt, or computational cost factor. This design allows an attacker to compare known plaintext-to-ciphertext mappings and recover the transformation logic.

Attack Vector

Exploitation requires local access with low privileges to the system where STER software stores credentials. The attacker reads the encoded password storage, supplies known passwords to observe their encoded forms, and then reverses the algorithm. No user interaction is required. The attack complexity is high because the attacker must analyze multiple encoded samples to derive the scheme. Successful exploitation impacts confidentiality of stored credentials but does not directly modify integrity or availability.

No public proof-of-concept code has been released, and no exploitation in the wild has been reported. Technical details are referenced in the CERT Polska analysis and the CIOP resource information page.

Detection Methods for CVE-2026-25607

Indicators of Compromise

• Unexpected local read access to STER software configuration files or credential storage locations
• Process activity from non-administrative accounts inspecting STER binaries or password stores
• Lateral movement or privilege escalation attempts following access to a host running STER

Detection Strategies

• Audit file access events on STER credential storage paths and alert on reads by non-service accounts
• Monitor for repeated read operations against the same credential file, which may indicate algorithm analysis
• Correlate local logon activity with subsequent file access to STER directories using endpoint telemetry

Monitoring Recommendations

• Enable detailed object access auditing on the host running STER software
• Forward endpoint and file access logs to a centralized log platform for retention and correlation
• Track installed STER versions across the environment and alert when versions earlier than 9.5 are detected

How to Mitigate CVE-2026-25607

Immediate Actions Required

• Upgrade STER software to version 9.5 or later on all affected hosts
• Rotate all passwords that were previously stored or processed by vulnerable STER versions
• Restrict local access to systems running STER to authorized administrative personnel only
• Review historical access logs for unauthorized reads of STER credential storage

Patch Information

The vendor fixed CVE-2026-25607 in STER software version 9.5. Administrators should apply this version across all deployments. Refer to the CERT Polska advisory and the CIOP resource page for vendor guidance.

Workarounds

• Apply strict file system permissions to STER credential storage to limit access to the service account
• Isolate hosts running vulnerable STER versions on segmented network zones until patching is complete
• Disable shared or interactive local accounts on systems that process STER credentials

# Configuration example: restrict file permissions on credential storage
chown ster-service:ster-service /opt/ster/config/credentials.dat
chmod 600 /opt/ster/config/credentials.dat