Cyber Resilience

CVE-2026-40866

High

Published: 21 April 2026

Published
21 April 2026
Modified
22 April 2026
KEV Added
Patch
CVSS Score v4 8.6 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/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
EPSS Score 0.0021 10.7th percentile
Risk Priority 55 floored blend · peak EPSS

Summary

CVE-2026-40866 is a high-severity Improper Access Control (CWE-284) vulnerability. Its CVSS base score is 8.6 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Stored Data Manipulation (T1565.001); ranked at the 10.7th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

OWASP Top 10 for Web (2025)

EU & UK References

Vulnerability details

Horilla is a free and open source Human Resource Management System (HRMS). In 1.5.0, an insecure direct object reference in the employee document upload endpoint allows any authenticated user to overwrite or replace or corrupt another employee’s document by changing…

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the document ID in the upload request. This enables unauthorized modification of HR records.

CWE(s)

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1565.001 Stored Data Manipulation Impact
Adversaries may insert, delete, or manipulate data at rest in order to influence external outcomes or hide activity, thus threatening the integrity of the data.
Why these techniques?

IDOR in document upload directly enables unauthorized stored data modification of HR records by authenticated users.

Confidence: MEDIUM · MITRE ATT&CK Enterprise v19.0

Affected Assets

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

addresses: CWE-284 CWE-639

Ensuring access control decisions are made and applied to every request before enforcement directly prevents improper access control by requiring policy-based checks.

addresses: CWE-284 CWE-639

Enforcing approved authorizations directly implements access control policies to block unauthorized access.

addresses: CWE-284

The access control policy and procedures directly mandate and enforce proper access control mechanisms across the organization.

addresses: CWE-284

Device lock enforces restricted access until re-authentication, directly reducing unauthorized use of active sessions.

addresses: CWE-284

Supervision and review of access control activities directly detects and remediates improper access configurations or usages.

addresses: CWE-284

Explicitly identifying and documenting actions permitted without identification or authentication enforces proper access control boundaries by defining justified exceptions.

addresses: CWE-284

By automatically labeling outputs with security attributes, the control supports attribute-based enforcement and reduces exploitability of improper access control weaknesses.

addresses: CWE-284

Associating and retaining security attributes with data directly supports enforcement of access control decisions across storage, processing, and transmission.

References