Bug 2571281 (CVE-2026-126085) - CVE-2026-126085 activestorage: Active Storage: File size validation bypass via missing direct-upload content length constraints
Summary: CVE-2026-126085 activestorage: Active Storage: File size validation bypass vi...
Keywords:
Status: NEW
Alias: CVE-2026-126085
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
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Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-11-10 21:21 UTC by OSIDB Bzimport
Modified: 2026-11-11 01:41 UTC (History)
10 users (show)

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Description OSIDB Bzimport 2026-11-10 21:21:53 UTC
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::Service::GCSService#url_for_direct_upload does not bind the declared content length into the signed direct-upload URL, and #headers_for_direct_upload returns no length constraint, so the URL authorizes an upload body of any size. A direct-upload client could store a file larger than the byte_size it declared, and the resulting blob keeps the declared size, possibly bypassing application file size validations and quotas. This is the weakness that CVE-2020-8162 fixed in the S3 service. Applications that store files in Google Cloud Storage and accept direct uploads are affected. This issue is fixed in versions 8.1.4.1 and 8.0.5.2.


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