openSIS Classic 9.3 contains an insecure direct object reference vulnerability in the messaging module. Any 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.
CVE-2026-8406
HIGHPre-NVD 7.17.1—
EchelonGraph scoreMEDIUM confidence
This high-severity CVE scores 7.1 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.2%, top 85% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
Triggered by: NVD CVSS baseline
Sources: epss, secondary
7.1
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
- High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 7.1Exploit: NoneExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 7.1
- EG Score
- 7.1(medium)
- EPSS
- 14.8%
- KEV
- Not listed
Published
June 11, 2026
Last Modified
June 11, 2026
Advisory Details (3)
Auto-updated Jun 11, 2026Upstream fix merged — awaiting tagged release. Sources: github_commit.
generic
openSIS Classic 9.3 - Insecure Direct Object Reference in Sent Mail | Fluid Attacks
https://fluidattacks.com/es/advisories/melaniegithub_commit
commit c45d43146167 (OS4ED/openSIS-Classic)
Fix landed in OS4ED/openSIS-Classic commit c45d43146167 — awaiting tagged release
https://github.com/OS4ED/openSIS-Classic/commit/c45d43146167324bae06bdf09de3e4bd2e5e478fgeneric
GitHub - OS4ED/openSIS-Classic: openSIS is a commercial grade, secure, scalable & intuitive Student Information System, School Management Software from OS4ED. Has all functionalities to run single or multiple institutions in one installation. Web based, php code, MySQL database. · GitHub
https://github.com/OS4ED/openSIS-ClassicVendor Advisories for CVE-2026-8406(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Frequently asked(5)
What is CVE-2026-8406?
CVE-2026-8406 is a high vulnerability published on June 11, 2026. openSIS Classic 9.3 contains an insecure direct object reference vulnerability in the messaging module. Any 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.
When was CVE-2026-8406 disclosed?
CVE-2026-8406 was first published in the National Vulnerability Database on June 11, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-8406 actively exploited?
CVE-2026-8406 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 14.8% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-8406?
CVE-2026-8406 has a CVSS v3 base score of 7.1 (NVD).
How do I remediate CVE-2026-8406?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-8406, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-8406
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