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Authorization Bypass (IDOR)Weakness · CWE-639

CVE-2026-8406

HIGH · 7.1 CVSS v4.0 Published 2026-06-11
Patch available
A vendor patch is available. No clean upgrade release — apply the published patch.
See remediation →
77/100
Remediation priority · High
Remotely reachable Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis
How this class of weakness works · CWE-639

The application uses a user-supplied identifier to look up a record without checking that the requester actually owns it, so changing the identifier in a request returns someone else's data. This is the classic insecure-direct-object-reference — the change-the-ID-in-the-URL bug. Remediation is authorizing every object access against the acting user, not merely confirming they are logged in.

General guidance for the authorization bypass (idor) class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
Authentication
X
User interaction
None
Scope
X

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Patch available Apply the vendor patch
Vendor patch github.com →
Recommended fix Moderate confidence
  1. 1. Navigate to the openSIS-Classic repository at https://github.com/OS4ED/openSIS-Classic
  2. 2. Locate the commit c45d43146167324bae06bdf09de3e4bd2e5e478f in the repository history
  3. 3. Review the changes made in that commit to understand the authorization fix applied to modules/messaging/SentMail.php
  4. 4. Apply the same fix to the affected openSIS Classic 9.3 installation by modifying the SentMail.php file to add proper authorization checks before allowing access to mail_id parameters
  5. 5. Verify that the fix properly validates that the authenticated user owns or has permission to access the requested mail_id before returning any message details

Generated from the published advisory — verify against the referenced sources before acting.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-8406 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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