CVE-2026-42346

MEDIUM

Postiz: TOCTOU DNS rebinding bypasses all SSRF URL validation paths

Title source: cna
STIX 2.1

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.

References (3)

Core 3

Scores

CVSS v3 6.5
EPSS 0.0003
EPSS Percentile 8.2%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact partial

Details

CWE
CWE-918
Status published
Products (1)
gitroomhq/postiz-app >= 2.16.6, < 2.21.7
Published May 08, 2026
Tracked Since May 09, 2026