CVE-2026-1365: Sayax OSOS Authentication Bypass Flaw

CVE-2026-1365 Overview

CVE-2026-1365 is an information disclosure vulnerability in Sayax Energy Technologies Inc. OSOS. The flaw stems from the insertion of sensitive information into sent data, which enables an authentication bypass. An authenticated attacker with low privileges can exploit the weakness over the network to access confidential data that should not be exposed in application responses. The issue affects all OSOS versions through 09072026. The vendor was contacted regarding this disclosure but did not respond. The vulnerability is tracked under CWE-201: Insertion of Sensitive Information Into Sent Data.

Critical Impact
Attackers can bypass authentication controls by extracting sensitive information leaked in server responses, compromising confidentiality of the OSOS platform.

Affected Products

Sayax Energy Technologies Inc. OSOS through version 09072026

Discovery Timeline

2026-07-09 - CVE-2026-1365 published to NVD
2026-07-09 - Last updated in NVD database
Vendor status - Sayax Energy Technologies was contacted but did not respond to the disclosure

Technical Details for CVE-2026-1365

Vulnerability Analysis

The vulnerability resides in how OSOS handles data returned to clients during application flows. Sensitive information, which should remain server-side, is embedded within responses transmitted to the client. This information exposure enables an attacker to bypass authentication controls by extracting values that permit unauthorized access decisions. The Turkish Cyber Security Bulletin confirms the issue affects OSOS builds up to and including 09072026. Because exploitation requires only low-privileged network access with no user interaction, any account with basic access to the application can leverage the flaw. The impact is confined to confidentiality, with no direct effect on integrity or availability.

Root Cause

The root cause is improper handling of sensitive server-side data ([CWE-201]). OSOS transmits authentication-relevant or otherwise confidential values as part of client-visible responses. These values may include session identifiers, tokens, credentials, or authorization state that should be scoped to backend processing. An attacker inspecting network traffic or application responses can harvest these values and reuse them to bypass authentication mechanisms.

Attack Vector

Exploitation occurs over the network against an OSOS deployment. An attacker with a valid low-privileged account submits standard requests to the application. The server response includes sensitive fields that reveal authentication material or state. The attacker replays or reuses this material to authenticate as another identity, gain elevated access, or bypass access controls entirely. No user interaction and no elevated privileges are required.

No verified public proof-of-concept code is available for this vulnerability. Refer to the Turkish Cyber Security Bulletin advisory for additional technical details.

Detection Methods for CVE-2026-1365

Indicators of Compromise

Unexpected sensitive fields such as tokens, credentials, or internal identifiers observed in HTTP responses from OSOS endpoints.
Authentication events for accounts originating from unusual IP addresses or user agents shortly after normal API interactions.
Repeated reuse of session tokens or authorization values across distinct client sessions or source addresses.

Detection Strategies

Perform passive traffic inspection of OSOS responses to identify sensitive data leakage in JSON, XML, or HTML payloads.
Deploy web application firewall (WAF) rules that flag responses containing high-entropy strings, credential-like patterns, or session identifiers outside authenticated cookies.
Correlate authentication logs with response monitoring to detect anomalies suggesting reuse of leaked authentication material.

Monitoring Recommendations

Enable verbose logging on OSOS application servers and forward logs to a centralized analytics platform for correlation.
Monitor for spikes in authentication events per account, especially those following API calls returning large or unusual response bodies.
Alert on access to sensitive OSOS functions from accounts that recently performed reconnaissance-style requests.

How to Mitigate CVE-2026-1365

Immediate Actions Required

Restrict network exposure of OSOS interfaces to trusted management networks or VPN-accessible segments only.
Rotate credentials, session tokens, and API keys used by OSOS accounts to invalidate any material that may have been leaked.
Enforce least-privilege access on OSOS accounts and disable any dormant or unnecessary low-privileged accounts.

Patch Information

At the time of publication, Sayax Energy Technologies has not released a patch and did not respond to disclosure attempts. Track the Turkish Cyber Security Bulletin for updates on vendor remediation. Apply any future OSOS release that supersedes build 09072026 as soon as it becomes available.

Workarounds

Place OSOS behind a reverse proxy that strips or masks sensitive fields from outbound responses.
Implement WAF response filtering to remove tokens, credentials, and internal identifiers from client-facing payloads.
Segment OSOS from untrusted networks and require multi-factor authentication on all upstream access paths.

bash

# Example NGINX reverse proxy configuration to strip sensitive response headers
location /osos/ {
    proxy_pass http://osos-backend/;
    proxy_hide_header X-Auth-Token;
    proxy_hide_header X-Internal-Session;
    proxy_hide_header X-User-Secret;
    # Prevent caching of any leaked sensitive data
    add_header Cache-Control "no-store, no-cache, must-revalidate";
}