How severe is CVE-2026-40487?

CVE-2026-40487 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-2026-40487 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (13th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-40487?

CVE-2026-40487 affects Gitroom Postiz. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-40487?

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-2026-40487 have an EU (EUVD) identifier?

Yes. CVE-2026-40487 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-23634.

When was CVE-2026-40487 published?

CVE-2026-40487 was published on 2026-04-18 and last updated on 2026-06-17.

CVE-2026-40487

CVE-2026-40487 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% (13th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-23634
Weakness: CWE-79
Affected product: Gitroom Postiz
Published: 2026-04-18
Last modified: 2026-06-17

Description

Postiz is an AI social media scheduling tool. Prior to version 2.21.6, a file upload validation bypass allows any authenticated user to upload arbitrary HTML, SVG, or other executable file types to the server by spoofing the `Content-Type` header. The uploaded files are then served by nginx with a Content-Type derived from their original extension (`text/html`, `image/svg+xml`), enabling Stored Cross-Site Scripting (XSS) in the context of the application's origin. This can lead to session riding, account takeover, and full compromise of other users' accounts. Version 2.21.6 contains a fix.

Frequently asked questions

What is CVE-2026-40487?: Postiz is an AI social media scheduling tool. Prior to version 2.21.6, a file upload validation bypass allows any authenticated user to upload arbitrary HTML, SVG, or other executable file types to the server by spoofing the `Content-Type` header. The uploaded files are then served by nginx with a Content-Type derived from their original extension (`text/html`, `image/svg+xml`), enabling Stored Cross-Site Scripting (XSS) in the context of the application's origin. This can lead to session riding, account takeover, and full compromise of other users' accounts. Version 2.21.6 contains a fix.
How severe is CVE-2026-40487?: CVE-2026-40487 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-2026-40487 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (13th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-40487?: CVE-2026-40487 affects Gitroom Postiz. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-40487?: 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-2026-40487 have an EU (EUVD) identifier?: Yes. CVE-2026-40487 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-23634.
When was CVE-2026-40487 published?: CVE-2026-40487 was published on 2026-04-18 and last updated on 2026-06-17.

References

Affected products (1)

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

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