How severe is CVE-2026-42556?

CVE-2026-42556 has a CVSS 3.x base score of 8.9, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is high, integrity high, and availability low.

Is CVE-2026-42556 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (17th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-42556?

CVE-2026-42556 affects Gitroom Postiz. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-42556?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-42556 have an EU (EUVD) identifier?

Yes. CVE-2026-42556 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-28866.

When was CVE-2026-42556 published?

CVE-2026-42556 was published on 2026-05-08 and last updated on 2026-06-17.

CVE-2026-42556

CVE-2026-42556 is a high-severity vulnerability in Gitroom Postiz with a CVSS 3.x base score of 8.9. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.

Key facts

Severity: High (CVSS 3.x base score 8.9)
EPSS exploit prediction: 0% (17th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-28866
Weakness: CWE-79
Affected product: Gitroom Postiz
Published: 2026-05-08
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2026-42556?: 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.
How severe is CVE-2026-42556?: CVE-2026-42556 has a CVSS 3.x base score of 8.9, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is high, integrity high, and availability low.
Is CVE-2026-42556 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (17th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-42556?: CVE-2026-42556 affects Gitroom Postiz. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-42556?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-42556 have an EU (EUVD) identifier?: Yes. CVE-2026-42556 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-28866.
When was CVE-2026-42556 published?: CVE-2026-42556 was published on 2026-05-08 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:gitroom:postiz:2.21.6:*:*:*:*:*:*:*

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