CVE-2026-33741 — Cross-Site Scripting (XSS)
CVE-2026-33741 — EspoCRM is an open source customer relationship management application. Versions 9.3.3 and below allow authenticated users to upload SVG attachments through normal attachment-capable fields and later serve those SVG files as top-level inline documents through both the attachment and
What This Means For You
- If your environment is affected by CWE-79, review your exposure and prioritize patching based on your environment. Monitor vendor advisories for CVE-2026-33741 updates and patches.
Related ATT&CK Techniques
🛡️ Detection Rules
3 rules · 6 SIEM formats3 detection rules auto-generated for this incident, mapped to MITRE ATT&CK. Sigma YAML is free — export to any SIEM format via the Intel Bot.
EspoCRM SVG XSS Attachment Upload — CVE-2026-33741
title: EspoCRM SVG XSS Attachment Upload — CVE-2026-33741
id: scw-2026-05-19-ai-1
status: experimental
level: high
description: |
Detects the upload of SVG files to EspoCRM via the file upload endpoint, which is a key step in exploiting CVE-2026-33741. This rule specifically targets the mechanism used to upload malicious SVG attachments that can lead to stored XSS.
author: SCW Feed Engine (AI-generated)
date: 2026-05-19
references:
- https://shimiscyberworld.com/posts/nvd-CVE-2026-33741/
tags:
- attack.initial_access
- attack.t1190
logsource:
category: webserver
detection:
selection:
cs-uri|contains:
- '/index.php?module=file&action=upload'
cs-method:
- 'POST'
cs-uri-query|contains:
- 'module=file'
sc-status:
- '200'
selection_indicators:
uri|contains:
- '.svg'
condition: selection AND selection_indicators
falsepositives:
- Legitimate administrative activity
Source: Shimi's Cyber World · License & reuse
Indicators of Compromise
| ID | Type | Indicator |
|---|---|---|
| CVE-2026-33741 | vulnerability | CVE-2026-33741 |
| CWE-79 | weakness | CWE-79 |
Written by SCW Vulnerability Desk
Source & Attribution
| Source Platform | NVD |
| Channel | National Vulnerability Database |
| Published | May 19, 2026 at 22:16 UTC |
This content was curated and summarized by Shimi's Cyber World for informational purposes. It is not copied or republished in full. All intellectual property rights remain with the original author and source.
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