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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].

Sources and references

Verified primary and authoritative sources

  • CVE-2026-8406 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-8406

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-8406 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-8406

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.