PatchSiren cyber security CVE debrief
CVE-2026-8406 OS4ED CVE debrief
CVE-2026-8406 is a high-severity vulnerability in openSIS Classic 9.3. The vulnerability is caused by an insecure direct object reference in the messaging module. An authenticated user with access to the messaging module can request sent-message details from modules/messaging/SentMail.php by supplying an arbitrary mail_id value. The vulnerability has a CVSS score of 7.1 and is considered high severity. The CVE was published on 2026-06-11T14:16:32.930Z and last modified on 2026-06-11T16:16:25.377Z.
- Vendor
- OS4ED
- Product
- openSIS-Classic
- CVSS
- HIGH 7.1
- CISA KEV
- Not listed in stored evidence
- Original CVE published
- 2026-06-11
- Original CVE updated
- 2026-06-11
- Advisory published
- 2026-06-11
- Advisory updated
- 2026-06-11
Who should care
Users of openSIS Classic 9.3 should be aware of this vulnerability and take steps to mitigate it. Specifically, administrators of openSIS Classic 9.3 installations should review the messaging module and ensure that access to sent-message details is properly restricted.
Technical summary
The vulnerability is caused by an insecure direct object reference in the messaging module of openSIS Classic 9.3. This allows an authenticated user to access sent-message details by supplying an arbitrary mail_id value in a request to modules/messaging/SentMail.php.
Defensive priority
High
Recommended defensive actions
- Restrict access to the messaging module to only authorized users.
- Implement proper input validation and sanitization for the mail_id parameter in modules/messaging/SentMail.php.
- Consider upgrading to a newer version of openSIS Classic, if available.
Evidence notes
The CVE record and NVD detail can be found at [cve-org] and [nvd], respectively. Additional information can be found in the source references [ref-4], [ref-5], and [ref-6].
Official resources
CVE-2026-8406 was publicly disclosed on 2026-06-11.