CVE-2026-71250 — MEDIUM (4.3)

Vulnerability 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. Additionally, the validator resolves the target hostname once via gethostbyname() at validation time, but the actual outbound request (StandardWebhookSender.php, via Guzzle) re-resolves the hostname independently at send time, allowing a DNS-rebinding attacker to pass validation against a public IP and have the real request delivered to a private or internal address. The webhook response body is only written to a server-side debug log, not returned to the triggering user, so this is a blind SSRF primitive rather than one with direct response read-back.

CVSS Score

4.3

MEDIUM

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

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality

NONE

Integrity

LOW

Availability

NONE

Related Weaknesses (CWE)

CWE-918

References

https://github.com/firefly-iii/firefly-iii

FAQ

What is CVE-2026-71250?

CVE-2026-71250 is a vulnerability with a CVSS score of 4.3 (MEDIUM). 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 ...

How severe is CVE-2026-71250?

CVE-2026-71250 has been rated MEDIUM with a CVSS base score of 4.3/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-71250?

Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.