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

Quick assessment

Affected
gitroomhq postiz-app
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Gitroom Postiz是Gitroom开源的一个社交媒体日程安排工具。 Gitroom Postiz 2.16.6版本至2.21.7之前版本存在代码问题漏洞，该漏洞源于SSRF保护存在TOCTOU漏洞，可能导致攻击者通过DNS重新绑定将请求重定向到内部网络地址。

CVSS 6.5 · Medium EPSS 0.22% · P13

Affected Version Matrix 1

VendorProduct Version RangeStatus
gitroomhq postiz-app >= 2.16.6, < 2.21.7 affected
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I. Basic Information for CVE-2026-42346

Vulnerability Information
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Vulnerability Title
Postiz: TOCTOU DNS rebinding bypasses all SSRF URL validation paths
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
服务端请求伪造(SSRF)
Source: CVE Program / CVE List V5
Vulnerability Title
Gitroom Postiz 代码问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Gitroom Postiz是Gitroom开源的一个社交媒体日程安排工具。 Gitroom Postiz 2.16.6版本至2.21.7之前版本存在代码问题漏洞，该漏洞源于SSRF保护存在TOCTOU漏洞，可能导致攻击者通过DNS重新绑定将请求重定向到内部网络地址。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
gitroomhq postiz-app >= 2.16.6, < 2.21.7 -

II. Public POCs for CVE-2026-42346

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III. Intelligence Information for CVE-2026-42346

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Patches & Fixes for CVE-2026-42346 (1)

Vendor Advisories for CVE-2026-42346 (1)

Vendor Pages for CVE-2026-42346 (1)

Same Patch Batch · gitroomhq · 2026-05-08 · 3 CVEs total

CVE-2026-42298 10.0 CRITICAL Postiz: Arbitrary Code Execution and Token Exfiltration in pr-docker-build.yml via untrust
CVE-2026-42556 8.9 HIGH Postiz stored XSS in public preview page

IV. Related Vulnerabilities

Same product: postiz-app
Same vendor: gitroomhq
Same weakness: CWE-918

V. Comments for CVE-2026-42346

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