CVE-2026-40487CRITICAL 9.0EPSS p12.9%

CVE-2026-40487CVE-2026-40487

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.

Scoring

CVSS 3.19.0 (CRITICAL)
VectorCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
EPSS0.22% probability of exploitation · percentile 12.9% · 2026-06-19T12:03:05Z
Published2026-04-18
Last modified2026-04-23

Underlying weaknesses· 3

CWE-79CWE-345CWE-434

References

  1. https://github.com/gitroomhq/postiz-app/releases/tag/v2.21.6
  2. https://github.com/gitroomhq/postiz-app/security/advisories/GHSA-44wg-r34q-hvfx
  3. https://github.com/gitroomhq/postiz-app/security/advisories/GHSA-44wg-r34q-hvfx

3

TypeTargetConfidenceTier
WeaknessInsufficient Verification of Data Authenticitycwe-3450%live
WeaknessUnrestricted Upload of File with Dangerous Typecwe-4340%live
WeaknessImproper Neutralization of Input During Web Page Generation ('Cross-site Scripting')cwe-790%live

Related by meaning· 6

Nearest entities by semantic similarity across the cs-graph corpus.

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CVE-2026-42556
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CVE-2026-40168
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CVE-2025-53641
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CVE-2026-34577
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CVE-2026-42298
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CVE-2026-28683
Sourced from NVD + FIRST.org EPSS. Curated for EU compliance use cases by Adam Lundqvist, Founder at SQUR.