CVE-2026-33659 EspoCRM: SSRF via DNS Rebinding in Attachment fromImageUrl Endpoint Allows Internal Network Access
Authenticated attackers can exploit DNS rebinding in EspoCRM to bypass IP restrictions and access internal network services.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-33659?
CVE-2026-33659 is a low-severity server-side request forgery vulnerability in espocrm, published on 13 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
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.
Which versions are affected by CVE-2026-33659?
It affects 1 product.
Products include Espocrm Espocrm.
How do I fix CVE-2026-33659?
No fix has been published for CVE-2026-33659 yet. Limit exposure of the affected software until one is available.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-33659 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33659 exists.
Other vulnerabilities in espocrm
Sources
Also known as GHSA-6m4j-fwrx-crh7.