CVE-2026-40487

critical

Postiz is an AI social media scheduling tool.

Vendor / product: Gitroom — postiz

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.

CVSS

9.0

9.0 (CVSS v3.1)

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H

Severity source: NVD CVSS v3.1 (nvd@nist.gov)

Timeline (UTC)

Published: 2026-04-18 02:16

Modified: 2026-10-26 21:10

NVD status: Analyzed

Last synced 2 days ago

Verified against the source API 2026-10-27 07:07 UTC

Exploitation

Not listed in CISA KEV (as of last catalog sync)

Absence from KEV does not mean a CVE is not exploited. Exploitation status: unknown (no authoritative evidence in our sources).

Affected products

gitroom / postiz <2.21.6

Weakness classification (CWE)

CWE-79 CWE-345 CWE-434

Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.

Mitigation & advisories

Vendor advisory: https://github.com/gitroomhq/postiz-app/security/advisories/GHSA-44wg-r34q-hvfx

References

https://github.com/gitroomhq/postiz-app/releases/tag/v2.21.6 security-advisories@github.com
https://github.com/gitroomhq/postiz-app/security/advisories/GHSA-44wg-r34q-hvfx security-advisories@github.com
https://github.com/gitroomhq/postiz-app/security/advisories/GHSA-44wg-r34q-hvfx 134c704f-9b21-4f2e-91b3-4a467353bcc0

Data sources

NVD CVE API 2.0 — fetched 2026-10-27 07:07 UTC · record ↗

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