File Upload Vulnerability in Active Storage by Rails
CVE-2026-126188

3.7LOW

Key Information:

Vendor

Rails

Status
Rails
Vendor
CVE Published:
10 November 2026

What is CVE-2026-126188?

Active Storage, a component of the Rails framework, allows seamless file uploads and attachment handling in cloud services. A significant vulnerability exists in versions prior to 8.0.5.2 and 8.1 until 8.1.4.1, wherein the ActiveStorage::Previewer::VideoPreviewer, ActiveStorage::Analyzer::VideoAnalyzer, and ActiveStorage::Analyzer::AudioAnalyzer components fail to enforce restrictions on the demuxer during blob content handling with FFmpeg. This oversight enables attackers to exploit uploaded files by retaining a client-specified media type, leading to the potential disclosure of local media files when untrusted uploads are processed. To mitigate risks, it's crucial to upgrade to the patched versions 8.0.5.2 or 8.1.4.1.

Affected Version(s)

rails >= 8.1, < 8.1.4.1 < 8.1, 8.1.4.1

rails < 8.0.5.2 < 8.0.5.2

References

https://github.com/rails/rails/security/advisories/GHSA-3...
x_refsource_CONFIRM
https://github.com/rails/rails/commit/3b1f2627538dc597cd9...
x_refsource_MISC
https://github.com/rails/rails/commit/69aff80d115bbb9d1e8...
x_refsource_MISC

CVSS V3.1

Score:
3.7
Severity:
LOW
Confidentiality:
Low
Integrity:
None
Availability:
Low
Attack Vector:
Network
Attack Complexity:
High
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.