# 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.

- **Severity:** Medium 4.3 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 5 Aug 2026
- **Updated:** 10 Aug 2026
- **Also known as:** GHSA-q8pq-98hq-mg7f

## 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 (Server-Side Request Forgery)

## 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.

## Is CVE-2026-71250 being exploited?

There is no known exploitation of CVE-2026-71250 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-71250 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-71250 in the wild and no public exploit code.

Affected product: firefly-iii. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-71250/ (Markdown: https://insights.sbomify.com/CVE-2026-71250/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-71250
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-71250
- OSV: https://osv.dev/vulnerability/CVE-2026-71250

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-71250/
Summaries are generated and may contain mistakes; the official description above is the record.