What’s Vulnerable › Vulnerabilities

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

• Severity: medium (CVSS 5.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-04-02 · updated 2026-07-24
• Weakness: CWE-918

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.

Affected products

• gitroomhq postiz-app: before 2.21.4 — fixed in 2.21.4

How to fix

Upgrade to a fixed version: gitroomhq postiz-app 2.21.4. Check the vendor advisory for mitigations.

References

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

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