What’s Vulnerable › Vulnerabilities

CVE-2026-42346: Postiz: TOCTOU DNS rebinding bypasses all SSRF URL validation paths

• Severity: medium (CVSS 6.5 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: none known
• Published: 2026-05-08 · updated 2026-07-24
• Weakness: CWE-918

Description

Postiz is an AI social media scheduling tool. From version 2.16.6 to before version 2.21.7, all SSRF protections added in v2.21.4–v2.21.6 share a fundamental TOCTOU (Time-of-Check-Time-of-Use) vulnerability: isSafePublicHttpsUrl() resolves DNS to validate the target IP, but subsequent fetch() calls resolve DNS independently. An attacker controlling a DNS server can exploit this gap via DNS rebinding to redirect requests to internal network addresses. This issue has been patched in version 2.21.7.

Affected products

• gitroomhq postiz-app: from 2.16.6, < 2.21.7

References

• https://github.com/gitroomhq/postiz-app/commit/071143dcb01cdeb9d5d7019892f4c6ff7b19dbeb
• https://github.com/gitroomhq/postiz-app/releases/tag/v2.21.7
• https://github.com/gitroomhq/postiz-app/security/advisories/GHSA-f7jj-p389-4w45

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