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CVE-2026-42556: Postiz stored XSS in public preview page

Analyzed
Published 08-05-2026Last modified 13-05-2026

Vulnerability summary

CVE-2026-42556 is a critical (CVSS 9.0) Cross-site Scripting vulnerability in gitroom postiz. EPSS estimates a 0.44% chance of exploitation in the next 30 days, higher than 37% of scored vulnerabilities.

Overall risk
70/100
0100
High · default modelHow is this calculated?
CVSS score
9.0/10
010
Critical · v3.1 (NVD)
EPSS score
0.44%
0%100%
Low · +0.18 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. 13-05-2026
    Last modifiedVulnerability information updated.

Description

Postiz is an AI social media scheduling tool. From version 2.21.6 to before version 2.21.7, any authenticated user who can create a post can store arbitrary HTML in post content by tampering their own save request and send the public preview link /p/<postId>?share=true to another user. The preview page renders that stored HTML with dangerouslySetInnerHTML on the main application origin. This issue has been patched in version 2.21.7.

CVSS metrics

2 scores · 2 sources · 1 version

EPSS trend

Probability

0.44%

Chance of exploitation in the next 30 days

Percentile

37%

Versus all other CVEs

30-day change

Increase +0.18 pp

From 0.26% 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

Gitroom1 product
Gitroomhq1 product

2 vendors · 2 products

References

2 links