EspoCRM: SSRF via DNS Rebinding in Attachment fromImageUrl Endpoint Allows Internal Network Access

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Summary

CVECVE-2026-33659
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-13 21:16:24 UTC
Updated2026-04-13 21:16:24 UTC
DescriptionEspoCRM 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.

Risk And Classification

Primary CVSS: v3.1 3.5 LOW from [email protected]

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

Problem Types: CWE-367 | CWE-918 | CWE-918 CWE-918: Server-Side Request Forgery (SSRF) | CWE-367 CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary3.5LOWCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:N/A:N
3.1CNADECLARED3.5LOWCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:N/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Changed
Confidentiality
Low
Integrity
None
Availability
None

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Espocrm Espocrm affected < 9.3.4 Not specified

References

ReferenceSourceLinkTags
github.com/espocrm/espocrm/security/advisories/GHSA-6m4j-fwrx-crh7 [email protected] github.com
github.com/espocrm/espocrm/commit/dca03cc3458e487362c26c746378a2d4de9990b1 [email protected] github.com
github.com/espocrm/espocrm/releases/tag/9.3.4 [email protected] github.com
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