CVE-2026-71250 Firefly III - Webhook URL Validation Explicitly Allows Loopback and Is Bypassable via DNS Rebinding
Authenticated users can bypass webhook URL validation to target loopback services, enabling Server-Side Request Forgery attacks against internal resources.
- 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-2026-71250?
CVE-2026-71250 is a medium-severity server-side request forgery vulnerability in firefly-iii, published on 5 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Firefly III's webhook URL validator (IsValidWebhookUrl.php) filters most private/reserved IPv4 ranges but contains an explicit early-return that allows any resolved address in 127.0.0.0/8, permitting an authenticated user (with webhooks enabled, which is off by default) to configure a webhook targeting loopback services on the server.
Weakness: CWE-918
Which versions are affected by CVE-2026-71250?
How do I fix CVE-2026-71250?
No fix has been published for CVE-2026-71250 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-2026-71250 being exploited?
There is no known exploitation of CVE-2026-71250 in the wild and no public exploit code.
Sources
Also known as GHSA-q8pq-98hq-mg7f.