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

Vulnerability summary

CVE-2026-34590 is a medium (CVSS 5.4) Server-Side Request Forgery (SSRF) vulnerability in gitroom postiz. EPSS estimates a 0.33% chance of exploitation in the next 30 days, higher than 24.9% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 02-04-2026
   PublishedVulnerability first disclosed.
2. 03-04-2026
   Last modifiedVulnerability information updated.

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.

• CWE-918Server-Side Request Forgery (SSRF)The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.