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.
- 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-2026-34590?
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
Which versions are affected by CVE-2026-34590?
It affects 1 product.
Products include 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.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
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 Postiz: Arbitrary Code Execution and Token Exfiltration in pr-docker-build.yml via untrusted Dockerfile.dev
- CVE-2026-42556 Postiz stored XSS in public preview page
- CVE-2026-40487 Postiz Has Unrestricted File Upload via MIME Type Spoofing that Leads to Stored XSS
- CVE-2026-34577 Postiz: Unauthenticated Full-Read SSRF via /public/stream Endpoint with Trivially Bypassable Extension Check
- CVE-2026-34576 Postiz: SSRF in upload-from-url endpoint allows fetching internal resources and cloud metadata
Sources
Also known as GHSA-wc9c-7cv8-m225.