CVE-2026-33657

Published: Apr 13, 2026 Last Modified: Apr 13, 2026
ExploitDB:
Other exploit source:
Google Dorks:
MEDIUM 4,6
Attack Vector: network
Attack Complexity: low
Privileges Required: low
User Interaction: required
Scope: unchanged
Confidentiality: low
Integrity: low
Availability: none

Description

AI Translation Available

EspoCRM is an open source customer relationship management application. Versions 9.3.3 and below have a stored HTML injection vulnerability that allows any authenticated user with standard (non-administrative) privileges to inject arbitrary HTML into system-generated email notifications by crafting malicious content in the post field of stream activity notes. The vulnerability exists because server-side Handlebars templates render the post field using unescaped triple-brace syntax, the Markdown processor preserves inline HTML by default, and the rendering pipeline explicitly skips sanitization for fields present in additionalData, creating a path where attacker-controlled HTML is accepted, stored, and rendered directly into emails without any escaping. Since the emails are sent using the system's configured SMTP identity (such as an administrative sender address), the injected content appears fully trusted to recipients, enabling phishing attacks, user tracking via embedded resources like image beacons, and UI manipulation within email content. The @mention feature further increases the impact by allowing targeted delivery of malicious emails to specific users. This issue has been fixed in version 9.3.4.

EPSS (Exploit Prediction Scoring System)

Trend Analysis

EPSS (Exploit Prediction Scoring System)

Prevede la probabilità di sfruttamento basata su intelligence sulle minacce e sulle caratteristiche della vulnerabilità.

EPSS Score
0,0003
Percentile
0,1th
Updated

EPSS Score Trend (Last 3 Days)

80

Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)

Incomplete
Common Consequences
Security Scopes Affected:
Confidentiality Integrity Availability
Potential Impacts:
Read Application Data Execute Unauthorized Code Or Commands
Applicable Platforms
Technologies: Web Based, Web Server
View CWE Details
116

Improper Encoding or Escaping of Output

Draft
Common Consequences
Security Scopes Affected:
Integrity Confidentiality Availability Access Control
Potential Impacts:
Modify Application Data Execute Unauthorized Code Or Commands Bypass Protection Mechanism
Applicable Platforms
Technologies: AI/ML, Database Server, Not Technology-Specific, Web Server
View CWE Details
https://github.com/espocrm/espocrm/security/advisories/GHSA-8prm-r5j9-j574
https://github.com/espocrm/espocrm/releases/tag/9.3.4
https://github.com/espocrm/espocrm/security/advisories/GHSA-8prm-r5j9-j574