How severe is CVE-2026-8406?

CVE-2026-8406 has a CVSS 4.0 base score of 7.1, rated high severity.

Is CVE-2026-8406 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-8406?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-8406 have an EU (EUVD) identifier?

Yes. CVE-2026-8406 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-36245.

When was CVE-2026-8406 published?

CVE-2026-8406 was published on 2026-06-11 and last updated on 2026-06-17.

CVE-2026-8406

CVE-2026-8406 is a high-severity vulnerability with a CVSS 4.0 base score of 7.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-639.

Key facts

Severity: High (CVSS 4.0 base score 7.1)
EPSS exploit prediction: 0% (15th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-36245
Weakness: CWE-639
Published: 2026-06-11
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2026-8406?: 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.
How severe is CVE-2026-8406?: CVE-2026-8406 has a CVSS 4.0 base score of 7.1, rated high severity.
Is CVE-2026-8406 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-8406?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-8406 have an EU (EUVD) identifier?: Yes. CVE-2026-8406 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-36245.
When was CVE-2026-8406 published?: CVE-2026-8406 was published on 2026-06-11 and last updated on 2026-06-17.

References

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