CVE intelligence and bounded remediation

CVE-2026-33740 — EspoCRM is an open source customer relationship management application

Medium CVSS 5.4

EspoCRM is an open source customer relationship management application. In versions 9.3.3 and below, the POST /api/v1/Email/importEml endpoint contains an Insecure Direct Object Reference (IDOR) vulnerability where the attacker-supplied fileId parameter is used to fetch any attachment directly from the repository without verifying that the current user has authorization to access it. Any authenticated user with Email:create and Import permissions can exploit this to read another user's .eml attachment contents by importing them as a new email into the attacker's mailbox, while the original victim attachment record is deleted as a side effect of the import flow. This is inconsistent with the standard attachment download path, which enforces ACL checks before returning file data, and is practically exploitable because attachment IDs are commonly exposed in normal UI and API workflows such as stream payloads and download links. This issue is fixed in version 9.3.4.

Severity
Medium
CVSS
5.4 (3.1)
Published
2026-04-13
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-639

Affected products

  • espocrm / espocrm

Matched remediation archetype

Authorization bypass, IDOR, and cross-tenant access

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Map object and action authorization checks across API, UI, batch, import/export, and background-job paths.
  • Identify tenant, ownership, role, and policy boundaries for affected resources and administrative operations.
  • Use synthetic fixtures to compare intended access matrices without accessing another user's real data.

Remediate safely

  • Enforce server-side authorization at each resource access and state transition using the authenticated principal and trusted tenant context.
  • Scope data queries by tenant and ownership; treat client-supplied identifiers, roles, and policy claims as untrusted.
  • Add deny-by-default policy tests for horizontal and vertical access across every affected transport.

Authoritative sources

Complete CVE record and remediation plan

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