CVE-2026-126074 Active Storage: Possible DoS vulnerability in Active Storage filename handling
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-126074?
CVE-2026-126074 is a medium-severity vulnerability in rails, published on 10 Nov 2026.
Official description
Active Storage makes it simple to upload and reference files in cloud services and attach those files to Active Record objects. Prior to 8.1.4.1 and 8.0.5.2, ActiveStorage::Filename#base and #extension_with_delimiter, and therefore #extension, pass the stored filename unmodified to File.basename and File.extname, which raise ArgumentError when the name contains a NUL byte. Active Storage stores the client-supplied filename verbatim, so a user who is permitted to upload an attachment could persist such a filename on databases that accept NUL bytes in string columns, such as SQLite and MySQL/MariaDB. Each subsequent request that builds a variant or preview of the blob, opens it, or renders it as an Action Text attachment then raises, possibly resulting in a persistent DoS vulnerability for the pages that display the blob until it is purged or its filename is corrected. Applications that use PostgreSQL are not affected, because PostgreSQL rejects the row. This issue is fixed in versions 8.1.4.1 and 8.0.5.2.
Weakness: CWE-248
Which versions are affected by CVE-2026-126074?
2 open source packages ship an affected version, including activestorage.
| Package | Affected | Fixed in |
|---|---|---|
activestorage RubyGems | All versions | 8.0.5.2 |
activestorage RubyGems | From 8.1.0.beta1 | 8.1.4.1 |
How do I fix CVE-2026-126074?
Upgrade activestorage to a fixed version for your release line: 8.0.5.2 or 8.1.4.1.
Is CVE-2026-126074 being exploited?
There is no known exploitation of CVE-2026-126074 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-126074, GHSA-p2pm-g2h6-7j5j, UBUNTU-CVE-2026-126074.