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Cross-site Scripting (XSS)Weakness · CWE-79

CVE-2026-33741

MEDIUM · 6.8 CVSS v3.1 Published 2026-05-19
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
72/100
Remediation priority · Elevated
Remotely reachable

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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 image entry points, resulting in stored cross-user XSS reachable through a normal attachment workflow. Although inline SVG script is blocked by the response CSP, the same CSP still allows same-origin external script. As a result, an attacker can upload a malicious SVG together with a second attacker-controlled JavaScript attachment, then trick another user into opening the SVG to execute JavaScript in the victim's EspoCRM origin. This issue has been fixed in version 9.3.4.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

EspoCRM versions 9.3.3 and below allow authenticated users to upload malicious SVG attachments through standard file upload fields. These SVG files are served as top-level inline documents, enabling stored cross-user XSS. While inline SVG script is blocked by CSP, the same policy permits same-origin external scripts, allowing attackers to upload a malicious SVG alongside a second attacker-controlled JavaScript file and achieve code execution in victims' browser sessions.

MitigationUpgrade to EspoCRM version 9.3.4, or alternatively disable SVG file type uploads, implement strict SVG sanitization, and enforce a CSP that blocks same-origin scripts.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
Low
Availability
Low

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:L/A:L

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed EspoCRM version
    Locate the version file in your EspoCRM installation (typically in data/config.php or a version.php file in the root/includes directory) or access the About page in the admin panel
    Affected if The installed version is 9.3.3 or any earlier version
  2. Verify SVG file upload capability is enabled
    Check the Attachment field configurations in the entity manager (Administration > Entity Manager > select an entity > fields) or inspect the MIME type allowlist in data/config.php to confirm .svg is permitted
    Affected if SVG files can be uploaded as attachments to any entity (Note, this is the default behavior in affected versions)
  3. Inspect Content-Disposition header for uploaded SVG files
    Upload a test SVG file to EspoCRM, then retrieve it via the API or browser dev tools and examine the response headers for Content-Disposition: inline versus Content-Disposition: attachment
    Affected if The header shows 'Content-Disposition: inline' or is missing entirely, allowing the browser to render the SVG directly
  4. Check Content-Security-Policy header configuration
    Access any EspoCRM page and inspect response headers (via browser dev tools or curl -I) for the CSP header; examine if script-src allows same-origin ('self') without strict restrictions on SVG-loaded scripts
    Affected if CSP allows 'self' as a script source and does not explicitly block external scripts loaded from SVG files

You are affected if EspoCRM version is 9.3.3 or below AND users can upload SVG attachments that are served inline (not as attachments), particularly if the CSP permits same-origin scripts.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade to EspoCRM version 9.3.4, or alternatively disable SVG file type uploads, implement strict SVG sanitization, and enforce a CSP that blocks same-origin scripts.

Recommended fix High confidence

9.3.4

  1. 1. Back up your existing EspoCRM installation and database before upgrading.
  2. 2. Download EspoCRM version 9.3.4 from the official repository or release page.
  3. 3. Replace the existing application files with the new version 9.3.4 files, preserving your configuration and data.
  4. 4. Run any database migration scripts included in the upgrade if applicable.
  5. 5. Verify the upgrade was successful by logging in and checking the version number.
  6. 6. Confirm that SVG file uploads are now properly sanitized and that the CSP blocks same-origin external scripts.

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-33741 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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