CVE-2026-33534

What it is

EspoCRM is an open source customer relationship management application. Versions 9.3.3 and below have an authenticated Server-Side Request Forgery (SSRF) vulnerability that allows bypassing the internal-host validation logic by using alternative IPv4 representations such as octal notation (e.g., 0177.0.0.1 instead of 127.0.0.1). This is caused by HostCheck::isNotInternalHost() function relying on PHP's filter_var(..., FILTER_VALIDATE_IP), which does not recognize alternative IP formats, causing the validation to fall through to a DNS lookup that returns no records and incorrectly treats the host as safe, however the cURL subsequently normalizes the address and connects to the loopback destination. Through the confirmed /api/v1/Attachment/fromImageUrl endpoint, an authenticated user can force the server to make requests to loopback-only services and store the fetched response as an attachment. This vulnerability is distinct from CVE-2023-46736 (which involved redirect-based SSRF) and may allow access to internal resources reachable from the application runtime. 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. Limited direct impact.

Exploit odds

2.0% 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: 2.0% in the next 30 days (EPSS).
• Severity: 4.3 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

2.0% · EPSS, next 30 days

Weakness

CWE-918 · Server-side request forgery

Record status

Analyzed

Affected

• Espocrm < 9.3.4

Attack profile CVSS 3.1 · 4.3

Attack vector

Network

Complexity

Low

Privileges needed

Low

User interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

None

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-2026-33534.md and follow it. Check whether this project is affected by CVE-2026-33534. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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