CVE-2026-40487: Postiz is an AI social media scheduling tool

Q: How do I fix CVE-2026-40487?

postiz: upgrade to 2.21.6. Exact commands for each OS are on this page.

Q: Is CVE-2026-40487 being exploited?

CVE-2026-40487 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-40487 affect?

CVE-2026-40487 affects postiz. Severity is high (CVSS 8.9). 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`

Q: How urgent is CVE-2026-40487?

Priority 39/100. High severity; Public exploit reference

Routine

HIGH 8.9UPGRADE

CVE-2026-40487 is a high-severity flaw (CVSS 8.9) affecting postiz. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 app

Why this priority

High severity
Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	8.9 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	Required
EPSS exploit chance	0.2% (top 87%)
CISA exploited list	No
Weakness	CWE-79, CWE-345, CWE-434
Published	2026-04-18
Last modified	2026-10-26

Publisher (CNA): GitHub, Inc. · Vendor: gitroom

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-18 02:16 UTCPublished CVE record published
2026-10-26 21:10 UTCUpdated Record last modified

gitroom postiz UPGRADE

Affected: < 2.21.6

Fixed in: 2.21.6

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy postiz || rpm -q postiz || postiz --version

2. UPGRADE to 2.21.6 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade postiz

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade postiz

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-40487?

postiz: upgrade to 2.21.6. Exact commands for each OS are on this page.

Is CVE-2026-40487 being exploited?

CVE-2026-40487 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-40487 affect?

CVE-2026-40487 affects postiz. Severity is high (CVSS 8.9). 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`

How urgent is CVE-2026-40487?

Priority 39/100. High severity; Public exploit reference

Software pages

nginx vulnerabilities

Related CVEs

CVE-2026-40168 HIGH 8.2 UPGRADE Postiz is an AI social media scheduling tool

References

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