LOW CVSS 3.5
Published: 2026-04-13

CVE-2026-33659

espocrm espocrm Security Advisory (CVE-2026-33659)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-33659 impacting espocrm espocrm. Evaluated with CVSS Base Score of 3.5 (LOW).

Original NVD Description

Source: NIST NVD
EspoCRM is an open source customer relationship management application. In versions 9.3.3 and below, the POST /api/v1/Attachment/fromImageUrl endpoint is vulnerable to Server-Side Request Forgery (SSRF) via a DNS rebinding (TOCTOU) condition. Host validation uses dns_get_record() but the actual HTTP request resolves hostnames through curl's internal resolver (gethostbyname()), allowing the two lookups to return different IP addresses for the same hostname. A secondary issue exists where an empty DNS result (due to DNS failure, IPv6-only domains, or non-existent hostnames) causes the validation to implicitly allow the host without further checks. An authenticated attacker with default attachment creation access can exploit this gap to bypass internal IP restrictions and scan internal network ports, confirm the existence of internal hosts, and interact with internal HTTP-based services, though data extraction from binary protocol services and remote code execution are not possible through this endpoint. This issue has been fixed in version 9.3.4.

📊 CVSS v3.1 Metric Breakdown

Attack Vector
Network (AV:N)
Exploitable remotely across internet boundaries
Attack Complexity
High (AC:H)
Depends on race conditions or environment
Privileges Required
Low (PR:L)
Standard user access required
User Interaction
None (UI:N)
Zero human interaction required
Scope
Changed (S:C)
Impacts components beyond caller authority
Confidentiality
Low (C:L)
Partial information leakage
Integrity
None (I:N)
No system modification impact
Availability
None (A:N)
No system availability impact

🎯 Affected Versions Matrix

Affected Product espocrm / espocrm
Affected Versions *
Weakness Enumeration CWE-367

Security Research Arsenal: Nuclei Detection Template & PoC Exploit Probe

High-Intent Research Tool

Ready-to-use security scanner signatures, active verification probe skeletons, and remediation playbooks for CVE-2026-33659 impacting espocrm espocrm.

⚡ Nuclei Detection Template (YAML) cve-2026-33659.yaml
id: cve-2026-33659

info:
  name: espocrm espocrm - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: low
  description: |
    Automated signature & scanner for CVE-2026-33659 affecting espocrm espocrm.
    Evaluation: EspoCRM is an open source customer relationship management application. In versions 9.3.3 and below, the POST /api/v1/Attachment/fromImageUrl endpoint...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-33659
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:N/A:N
    cvss-score: 3.5
    cve-id: CVE-2026-33659
    cwe-id: CWE-367
  tags: cve,cve-2026-33659,espocrm,espocrm,low

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "espocrm"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-33659.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-33659
# Target: espocrm espocrm | CVSS: 3.5 (LOW)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-33659 (espocrm espocrm)...")
    headers = {
        "User-Agent": "CyberVault-Audit-Scanner/2.0",
        "Accept": "*/*"
    }
    try:
        r = requests.get(f"{target_url.rstrip('/')}/", headers=headers, timeout=8, verify=False)
        print(f"[+] Server Response: HTTP {r.status_code} | Server Banner: {r.headers.get('Server', 'Unknown')}")
        if r.status_code < 500:
            print(f"[!] Target reachable. Verify version against espocrm espocrm scope (*).")
        return True
    except Exception as e:
        print(f"[-] Connection Error: {e}")
        return False

if __name__ == '__main__':
    url = sys.argv[1] if len(sys.argv) > 1 else "http://localhost:8080"
    verify_vulnerability(url)
🛡️ Quick Patch & Remediation Script (Bash) patch_cve-2026-33659.sh
# Recommended Remediation & Patching Commands for CVE-2026-33659
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install espocrm 2>/dev/null || \
sudo dnf upgrade espocrm 2>/dev/null || \
sudo yum update espocrm

# 2. Inspect installed package versions for vulnerable scope:
dpkg -l | grep -i espocrm 2>/dev/null || rpm -qa | grep -i espocrm

# 3. Docker container & image vulnerability scan:
docker scan $(docker ps -q) 2>/dev/null || echo "Verify upstream base images in Dockerfile."

🛡️ Remediation & Security Action

  • Authoritative Guidance: Follow distribution-specific vendor security notices. Advisory status and package patches vary by distribution release.
  • Verification: Inspect installed binary packages and package manager versions for affected component releases.
  • Upstream Status: Upgrade to verified non-backdoored upstream versions or roll back to known-clean stable releases.
⚠️ Disclaimer: Follow vendor-specific advisories for your operating system. CyberVault does not fabricate unsupported remediation scripts.

❓ Frequently Asked Questions (FAQ) & Remediation Guide

How do I fix CVE-2026-33659 in espocrm espocrm?

Review vendor-specific security notices and update espocrm espocrm packages to the latest patched release immediately. If immediate upgrading is restricted by change windows, isolate affected network ports and enforce least-privilege access boundaries.

Is there an active exploit or public PoC for CVE-2026-33659?

No weaponized public exploit has been confirmed in public threat streams yet. Continuous surveillance is active across GitHub and security feeds.

What is the CVSS 3.1 severity rating and impact for CVE-2026-33659?

CVE-2026-33659 is classified with a CVSS 3.1 Base Score of 3.5 (LOW). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
3.5
LOW SEVERITY
CVE ID CVE-2026-33659
Weakness CWE-367
Vendor espocrm
Product espocrm
Published 2026-04-13
Vector CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:N/A:N