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TI-2026-26837 Aliases CVE-2026-34590

Postiz: SSRF via Webhook Creation Endpoint Missing URL Safety Validation

Priority MEDIUM 58CWE-918Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
Low · Low · None
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00234 14th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed postiz-app (gitroomhq): 2.21.4

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
gitroomhqpostiz-appbefore 2.21.42.21.4Patch availableCNA
  • postiz-app Vendorgitroomhq Affected before 2.21.4 Fixed in 2.21.4 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:gitroom:postiz:*:*:*:*:*:*:*:*before 2.21.4Vulnerablegitroomhq
  • cpe:2.3:a:gitroom:postiz:*:*:*:*:*:*:*:* Versions before 2.21.4 Vulnerable ·gitroomhq

Remediation

  • Fix · CNA postiz-app (gitroomhq) Fixed in 2.21.4

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-34590

References

Exploit 1

Patch 1

Other 1

  • TI-2026-26825 Postiz: Unauthenticated Full-Read SSRF via /public/stream Endpoint with Trivially Bypassable Extension Check CVSS 3.1HIGH 8.6
  • TI-2026-28982 Postiz has Server-Side Request Forgery via Redirect Bypass in /api/public/stream CVSS 3.1HIGH 8.2
  • TI-2026-29238 Postiz Has Unrestricted File Upload via MIME Type Spoofing that Leads to Stored XSS CVSS 3.1CRITICAL 9.0
  • TI-2026-26824 Postiz: SSRF in upload-from-url endpoint allows fetching internal resources and cloud metadata CVSS 4.0HIGH 8.3
  • TI-2026-30607 Postiz: Arbitrary Code Execution and Token Exfiltration in pr-docker-build.yml via untrusted Dockerfile.dev CVSS 3.1CRITICAL 10.0
  • TI-2026-30836 Postiz stored XSS in public preview page CVSS 3.1CRITICAL 9.0

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences