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Advisory record · GHSA-937x-gpqr-72gg

Flask-Reuploaded: Extension-denylist bypass via case-folding asymmetry in name-override path (incomplete-fix variant of CVE-2026-27641)

CVSS 7.5 HighEPSS 0.0063 · 50th percentile

Published by the GitHub Advisory Database at 17 Jul 2026, 20:11 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
flask-reuploadedPyPI<1.6.01.6.0
Identifiers
GHSA-937x-gpqr-72gg · CVE-2026-54567 · PYSEC-2026-3466
Weakness (CWE)
CWE-178 · CWE-434
Tags
Published
17 Jul 2026
Updated
23 Jul 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

flask-reuploaded before 1.6.0 does not apply the extension denylist correctly to a name override passed to UploadSet.save(), because the extension is compared case-sensitively. An attacker who controls that name can store files such as shell.PHP, which case-insensitive servers may execute. Upgrade to flask-reuploaded 1.6.0.

Written 5 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
7.5 High 3.1 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS 0.0063, the 50th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:41 UTC First seen by agentprime
  2. 31 Oct 2026, 14:41 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.