CVE-2026-33657Public exploitNetwork attack vector

Stored HTML injection via unescaped post rendering

Published Apr 13, 2026 · Updated Apr 13, 2026

Stored HTML injection in EspoCRM 9.3.3 and earlier allows remote authenticated users to place arbitrary HTML in notification emails. Server-side Handlebars templates render the stream-note post field with triple braces after Markdown preserves inline HTML and additionalData bypasses sanitization. A standard user account can target recipients through mentions; opening the trusted system email enables phishing, interface manipulation, and external-resource tracking.

CVSS severity4.6
Medium
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Stored HTML injection in EspoCRM 9.3.3 and earlier allows remote authenticated users to place arbitrary HTML in notification emails. Server-side Handlebars templates render the stream-note post field with triple braces after Markdown preserves inline HTML and additionalData bypasses sanitization. A standard user account can target recipients through mentions; opening the trusted system email enables phishing, interface manipulation, and external-resource tracking.

The record

CVE
CVE-2026-33657
Published
Apr 13, 2026
Updated
Apr 13, 2026
Vendor
EspoCRM
Product
EspoCRM
Classifications
CWE-80, CWE-116, T1566.002
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 13, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 13, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 9.3.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

EspoCRM · EspoCRMversion=< 9.3.4

Published CVSS scores

4.6GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N
5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-80Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)
CWE-116Improper Encoding or Escaping of Output
T1566.002Spearphishing Link

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo