# CVE-2026-34590: Postiz: SSRF via Webhook Creation Endpoint Missing URL Safety Validation

> Attackers can exploit missing URL validation in webhook creation to perform blind SSRF against internal services in Postiz.

- **Severity:** Medium 5.4 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/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:** 2 Apr 2026
- **Updated:** 3 Apr 2026
- **Also known as:** GHSA-wc9c-7cv8-m225

## What is CVE-2026-34590?

CVE-2026-34590 is a medium-severity server-side request forgery vulnerability in gitroomhq postiz-app, published on 2 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Postiz is an AI social media scheduling tool. Prior to version 2.21.4, the POST /webhooks/ endpoint for creating webhooks uses WebhooksDto which validates the url field with only @IsUrl() (format check), missing the @IsSafeWebhookUrl validator that blocks internal/private network addresses. The update (PUT /webhooks/) and test (POST /webhooks/send) endpoints correctly apply @IsSafeWebhookUrl. When a post is published, the orchestrator fetches the stored webhook URL without runtime validation, enabling blind SSRF against internal services. This issue has been patched in version 2.21.4.

Weakness: CWE-918 (Server-Side Request Forgery)

## Which versions are affected by CVE-2026-34590?

It affects 1 product.


Products: Gitroom Postiz.

## How do I fix CVE-2026-34590?

No fix has been published for CVE-2026-34590 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-34590 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-34590 exists.

## Other vulnerabilities in gitroomhq postiz-app

- [CVE-2026-42298](https://insights.sbomify.com/CVE-2026-42298/): Postiz: Arbitrary Code Execution and Token Exfiltration in pr-docker-build.yml via untrusted Dockerfile.dev (critical 10.0)
- [CVE-2026-42556](https://insights.sbomify.com/CVE-2026-42556/): Postiz stored XSS in public preview page (high 8.9)
- [CVE-2026-40487](https://insights.sbomify.com/CVE-2026-40487/): Postiz Has Unrestricted File Upload via MIME Type Spoofing that Leads to Stored XSS (high 8.9)
- [CVE-2026-34577](https://insights.sbomify.com/CVE-2026-34577/): Postiz: Unauthenticated Full-Read SSRF via /public/stream Endpoint with Trivially Bypassable Extension Check (high 8.6)
- [CVE-2026-34576](https://insights.sbomify.com/CVE-2026-34576/): Postiz: SSRF in upload-from-url endpoint allows fetching internal resources and cloud metadata (high 8.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-34590 and fix it if it is affected.

What it is: CVE-2026-34590 is a medium-severity server-side request forgery vulnerability in gitroomhq postiz-app, published on 2 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-34590 exists.

Affected product: gitroomhq postiz-app. 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-2026-34590/ (Markdown: https://insights.sbomify.com/CVE-2026-34590/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-34590
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-34590
- OSV: https://osv.dev/vulnerability/CVE-2026-34590

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-34590/
Summaries are generated and may contain mistakes; the official description above is the record.