CVE-2026-33656

CriticalPublic PoC

Published: 22 April 2026

Published

22 April 2026

Modified

27 April 2026

KEV Added

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Patch

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CVSS Score 9.1 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

EPSS Score 0.0007 21.6th percentile

Risk Priority 18 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2026-33656 is a critical-severity Path Traversal (CWE-22) vulnerability in Espocrm Espocrm. Its CVSS base score is 9.1 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 21.6th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified are NIST 800-53 SI-10 (Information Input Validation) and AC-6 (Least Privilege).

Threat & Defense at a Glance

What attackers do: exploitation maps to Exploit Public-Facing Application (T1190) and 2 other techniques. What defenders deploy: see the NIST 800-53 controls recommended below.

Threat & Defense Details

Mitigating Controls (NIST 800-53 r5)AI

SI-10 Information Input Validation good match

prevent

Directly mitigates the path traversal by requiring validation and sanitization of the unsanitized `sourceId` input before its use in file path construction.

AC-6 Least Privilege partial match

prevent

Enforces least privilege to restrict authenticated administrators from using the formula scripting engine to update sensitive `sourceId` fields unless operationally required.

SI-9 Information Input Restrictions partial match

prevent

Restricts `sourceId` inputs to whitelisted values, types, or formats that prevent inclusion of path traversal sequences like '../'.

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access

Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.

attack.mitre.org →

T1005 Data from Local System Collection

Adversaries may search local system sources, such as file systems, configuration files, local databases, virtual machine files, or process memory, to find files of interest and sensitive data prior to Exfiltration.

attack.mitre.org →

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.

attack.mitre.org →

Why these techniques?

Path traversal vuln in web app (T1190) allows unsanitized file read (T1005) and overwrite of critical data (T1565.001) within open_basedir.

Confidence: MEDIUM · MITRE ATT&CK Enterprise v18.1

NVD Description

EspoCRM is an open source customer relationship management application. Prior to version 9.3.4, EspoCRM's built-in formula scripting engine allowing updating attachment's sourceId thus allowing an authenticated admin to overwrite the `sourceId` field on `Attachment` entities. Because `sourceId` is concatenated directly…

into a file path with no sanitization in `EspoUploadDir::getFilePath()`, an attacker can redirect any file read or write operation to an arbitrary path within the web server's `open_basedir` scope. Version 9.3.4 fixes the issue.

Deeper analysisAI

CVE-2026-33656 is a path traversal vulnerability (CWE-22) affecting EspoCRM, an open source customer relationship management application, in versions prior to 9.3.4. The issue stems from the built-in formula scripting engine, which allows updating the `sourceId` field on `Attachment` entities. This `sourceId` value is concatenated directly into file paths without sanitization in the `EspoUploadDir::getFilePath()` function, enabling redirection of file read or write operations to arbitrary paths within the web server's `open_basedir` scope. The vulnerability has a CVSS v3.1 base score of 9.1 (AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H).

An authenticated administrator can exploit this vulnerability remotely with low complexity and no user interaction required. By overwriting the `sourceId` field via the formula scripting engine, the attacker can manipulate file paths, potentially reading sensitive files or overwriting critical data within the restricted `open_basedir` directory. The changed scope (S:C) amplifies impact across the system, leading to high confidentiality, integrity, and availability consequences.

The official GitHub security advisory (GHSA-7922-x7cf-j54x) confirms that EspoCRM version 9.3.4 addresses the issue by fixing the unsanitized handling of `sourceId` in the file path construction. Security practitioners should upgrade to version 9.3.4 or later and review access to formula scripting features for admin users.