6.5

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

Deferred
Published 08-05-2026Last modified 11-05-2026

Vulnerability summary

CVE-2026-42346 is a medium (CVSS 6.5) Server-Side Request Forgery (SSRF) vulnerability in gitroomhq postiz-app. EPSS estimates a 0.36% chance of exploitation in the next 30 days, higher than 28.8% of scored vulnerabilities.

Overall risk
26/100
0100
Medium · default modelHow is this calculated?
CVSS score
6.5/10
010
Medium · v3.1 (CVE.org)
EPSS score
0.36%
0%100%
Low · +0.14 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Timeline

  1. 08-05-2026
    PublishedVulnerability first disclosed.
  2. 11-05-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

2 scores · 2 sources · 1 version

EPSS trend

Probability

0.36%

Chance of exploitation in the next 30 days

Percentile

29%

Versus all other CVEs

30-day change

Increase +0.14 pp

From 0.22% on 23-09-2026

23-09-202623-10-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Gitroomhq1 product

1 vendor · 1 product

References

3 links