CVE-2026-33657

What it is

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.

At a glance

Exploitability

Can be exploited over the network with a low-privilege account, but needs a user to act. Limited direct impact.

Exploit odds

0.2% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-04-13 20:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 10:37 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.2% in the next 30 days (EPSS).
• Severity: 4.6 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-04-13 20:16 UTC

Last modified

2026-06-17 10:37 UTC

Exploit probability

0.2% · EPSS, next 30 days

Weakness

CWE-80

Record status

Analyzed

Affected

• Espocrm < 9.3.4

Attack profile CVSS 3.1 · 4.6

Attack vector

Network

Complexity

Low

Privileges needed

Low

User interaction

Required

Scope

Unchanged

Confidentiality

Low

Integrity

Low

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-33657.md and follow it. Check whether this project is affected by CVE-2026-33657. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

Copy as ticket · More options · Status badge