CVE-2026-56734 Zammad: Avatar Image URL Server-Side Request Forwarding
Attackers can force the Zammad server to connect to internal network locations via malicious profile image URLs during federated authentication, enabling internal service probing and potential denial of service.
- 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-2026-56734?
CVE-2026-56734 is a medium-severity server-side request forgery vulnerability in zammad, published on 25 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Zammad is a web based open source helpdesk/customer support system. Prior to 7.0.2, during federated authentication (OAuth/OIDC/SAML), a profile image URL from the external identity provider is fetched without verifying the target address. An actor who controls their profile at a connected provider may cause the server to connect to internal network locations. Response timing and error patterns differ between reachable and unreachable targets, allowing internal service probing. Worker processes may be blocked for several seconds per request. Requires a configured external authentication provider where the actor can modify their profile image URL. This issue is fixed in version 7.0.2.
Weakness: CWE-918
Which versions are affected by CVE-2026-56734?
How do I fix CVE-2026-56734?
No fix has been published for CVE-2026-56734 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-2026-56734 being exploited?
There is no known exploitation of CVE-2026-56734 in the wild and no public exploit code.
Sources
Also known as GHSA-q3cr-3wq3-29hx.