CVE-2026-54567Public exploitNetwork attack vectorHinoki check available

Dangerous file upload via case-sensitive denylist check

Published Sep 14, 2026 · Updated Sep 14, 2026

Dangerous file upload in Flask-Reuploaded 1.5.0 allows remote authenticated users to store denied file types via name overrides. UploadSet.save extracts a caller-supplied filename extension without lowercasing it, then compares it with lowercase AllExcept denylist entries. Exploitation requires a user-influenced override, a denylist, and case-insensitive extension handling; an execution-capable upload directory enables code execution with web-server privileges.

CVSS severity7.5
High
EPSS probability0.58%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Dangerous file upload in Flask-Reuploaded 1.5.0 allows remote authenticated users to store denied file types via name overrides. UploadSet.save extracts a caller-supplied filename extension without lowercasing it, then compares it with lowercase AllExcept denylist entries. Exploitation requires a user-influenced override, a denylist, and case-insensitive extension handling; an execution-capable upload directory enables code execution with web-server privileges.

The record

CVE
CVE-2026-54567
Published
Sep 14, 2026
Updated
Sep 14, 2026
Vendor
jugmac00
Product
Flask-Reuploaded
Classifications
CWE-434, CWE-178, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 14, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 14, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.6.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

jugmac00 · Flask-Reuploadedversion=< 1.6.0

Published CVSS scores

7.5GitHubCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-434Unrestricted Upload of File with Dangerous Type
CWE-178Improper Handling of Case Sensitivity
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo