CVE-2026-7491 Overview
CVE-2026-7491 is an Insecure Direct Object Reference (IDOR) vulnerability in the School App developed by Zyosoft. Authenticated remote attackers can modify a specific request parameter to read and modify other users' data. The flaw is tracked under CWE-639: Authorization Bypass Through User-Controlled Key. The vulnerability was published by TW-CERT and added to the National Vulnerability Database on 2026-05-02.
Critical Impact
Authenticated attackers can access and tamper with arbitrary user records by manipulating object identifiers, leading to confidentiality and integrity loss across the application's user base.
Affected Products
- Zyosoft School App
Discovery Timeline
- 2026-05-02 - CVE-2026-7491 published to NVD
- 2026-05-05 - Last updated in NVD database
Technical Details for CVE-2026-7491
Vulnerability Analysis
The School App exposes API or web endpoints that accept a user-controlled identifier referencing internal records. The application authenticates the request but fails to verify that the calling user owns or is authorized to access the referenced object. As a result, an attacker who holds any valid account can substitute another user's identifier and reach data belonging to that user.
Because the endpoint also processes write operations, the same parameter manipulation enables modification of other users' data. This expands the impact from information disclosure to tampering of records held by the application.
Root Cause
The root cause is missing object-level authorization. The server trusts the identifier supplied in the request without enforcing a server-side ownership or role check. This pattern is captured by [CWE-639]. The attack requires only low-privilege authenticated access and no user interaction.
Attack Vector
Exploitation occurs over the network against the application's authenticated interface. An attacker logs in with a legitimate account, intercepts a request that references their own record, and substitutes the identifier with a target value. The server returns or modifies the targeted record without rejecting the request. Technical details are described in the TW-CERT Security Advisory and the TW-CERT Incident Report. No public proof-of-concept exploit code is referenced in the advisory.
Detection Methods for CVE-2026-7491
Indicators of Compromise
- Authenticated sessions issuing repeated requests that iterate or fuzz numeric or sequential identifier parameters.
- Single user accounts retrieving or updating records associated with many distinct user IDs in a short window.
- Application audit logs showing read or write operations on records that do not match the authenticated principal's ownership.
Detection Strategies
- Inspect web server and application logs for parameter tampering patterns against endpoints that take user, student, or record identifiers.
- Correlate authenticated session identity with the object identifiers accessed and alert on mismatches.
- Deploy web application firewall rules that flag rapid enumeration of object identifiers per session.
Monitoring Recommendations
- Centralize application access logs and retain request parameters for forensic review.
- Track per-account access volume to user records and alert on outliers exceeding normal usage.
- Monitor unauthorized HTTP 200 responses on endpoints that should return 403 for cross-tenant access.
How to Mitigate CVE-2026-7491
Immediate Actions Required
- Contact Zyosoft to obtain the vendor-supplied fix and apply it to all School App deployments.
- Audit application logs since deployment for evidence of identifier manipulation against user records.
- Restrict access to the application to known networks or VPN until a patch is applied.
Patch Information
Review the TW-CERT Security Advisory for vendor remediation guidance. Operators should apply the fixed version distributed by Zyosoft and confirm that authorization checks are enforced on every endpoint that accepts a record identifier.
Workarounds
- Implement server-side authorization checks that validate the authenticated user owns or is permitted to access each referenced object.
- Replace sequential numeric identifiers with unguessable opaque values such as UUIDs to reduce enumeration risk.
- Add rate limiting on endpoints that accept identifier parameters to slow enumeration attempts.
- Force re-authentication or step-up authentication for sensitive write operations on user records.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
