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NVD / CVE Program· CNA GitHub_M

CVE-2026-33534: EspoCRM has authenticated SSRF via internal-host validation bypass using alternative IPv4 notation

Noroxi assessment

Priority: Monitor (action score 18/100)

  • A ready-made attack module is public (Nuclei); exploiting it takes no special expertise.
  • Public proof-of-concept code exists (Exploit-DB, GitHub); there is no record of exploitation in the wild.
  • Probability of exploitation in the next 30 days: 1.9% (FIRST EPSS); higher than 80.6% of all records.
  • Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: espocrm espocrm 9.3.4.

Low priority for now. Upgrade to espocrm espocrm 9.3.4 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

MediumCVSS 4.3 · v3.1—Proof of concept Fix available
Published
Apr 13, 2026
Updated
Jun 17, 2026
EPSS
1.9% · 80th percentile

Report tools

JSON

Action score

18

Monitor

Low priority for now.

CVSS
17 / 40 · 4.3 / 10
CISA KEV
0 / 30 · Not listed
EPSS
1 / 30 · 1.9%

CISA SSVC decision

Exploitation
proof of concept
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · GitHub_M
4.3
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • Proof of concept exists, no weaponized module
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-33534

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
espocrmespocrm

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • espocrm espocrmbefore 9.3.4

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • espocrm espocrm

    • < 9.3.4affected

Same product

espocrm: all records

Other highest-scoring records for the same primary product.

  • CVE-2014-7985Directory traversal vulnerability in EspoCRM before 2.6.0 allows remote attackers to include and execute arbitrary local files via a ..
    42Plan
  • CVE-2026-47168EspoCRM: Authenticated RCE via Unsafe PHP Object Deserialization in MassAction/Export params
    36Monitor
  • CVE-2026-33656EspoCRM vulnerable to authenticated RCE via Formula with path traversal in attachment `sourceId`, exploitable by admin user
    36Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2025-59428Oct 14, 2025 · EspoCRM allows arbitrary user creation via stored SVG injection and CSRF
    21Monitor
  • ← EarlierCVE-2020-37094Feb 3, 2026 · EspoCRM 5.7.0 < 5.9.0 - Two-Factor Authentication Bypass via Auth Token Reuse Between Accounts with Identical Passwords
    34Monitor
  • Later →CVE-2026-33657Apr 13, 2026 · EspoCRM: Stored HTML injection in email notifications about stream notes via unescaped post field
    21Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
espocrm espocrm9.3.4 · descriptionVendor (CNA)

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Exploit-DB entry ×1
  • Nuclei detection template ×1
  • Proof-of-concept repository on GitHub ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Exploit-DB entrywebapps2026-05-27
Nuclei detection templateNuclei template CVE-2026-33534 —
Proof-of-concept repository on GitHubstars:02026-05-08

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. Published
  2. First PoC+24 d
  3. TodayNov 7, 2026+208 d

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-88896150 days apartEspoCRM before 10.0.4 SSRF via IPv6 Transition Address Bypass
    27Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

  • CVE-2020-3709469 days apartEspoCRM 5.7.0 < 5.9.0 - Two-Factor Authentication Bypass via Auth Token Reuse Between Accounts with Identical Passwords
    34Monitor

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
low · data can be read
Integrity
none
Availability
none
Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
Low
Integrity impact
None
Availability impact
None

Weakness class (CWE)

CWE-918 · Server-Side Request Forgery (SSRF)

CVSS vector

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

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records