Firefly III - Webhook URL Validation Explicitly Allows Loopback and Is Bypassable via DNS Rebinding
Priority LOW 20CWE-918Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- None · Low · None
- Fix status
- No fix listed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA.
Summary
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.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00276 20th percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| firefly-iii | firefly-iii | all versions | — | No fix listed | CNA |
- firefly-iii Vendorfirefly-iii Affected all versions Fixed in — No fix listed CNA
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2026-71250
- 2026-10-03 Alias added: GHSA-q8pq-98hq-mg7f
References
More firefly-iii vulnerabilities
- TI-2023-01681 Improper Input Validation in firefly-iii/firefly-iii CVSS 3.1CRITICAL 9.8
- TI-2023-01680 Insufficient Session Expiration in firefly-iii/firefly-iii CVSS 3.1CRITICAL 9.8
- TI-2023-00283 Incorrect Authorization in firefly-iii/firefly-iii CVSS 3.1MEDIUM 6.5
- TI-2019-10251 Firefly III before 4.7.17.1 is vulnerable to stored XSS due to lack of filtration of… CVSS 3.1MEDIUM 5.4
- TI-2021-02811 Cross-Site Request Forgery (CSRF) in firefly-iii/firefly-iii CVSS 3.1HIGH 8.8
- TI-2021-02777 Unrestricted Upload of File with Dangerous Type in firefly-iii/firefly-iii CVSS 3.1HIGH 8.8
Sources
- CVE-2026-71250 · CVE Program
- CVE-2026-71250 · NVD
- FIRST EPSS
- GHSA-q8pq-98hq-mg7f · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences