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, when a GCS service is configured with the cache_control option, ActiveStorage::Service::GCSService#url_for_direct_upload signs direct-upload URLs with V4, and the V4 signature covers only the Cache-Control and Host headers. A direct-upload client can therefore send a Content-Type of its choosing, and can omit the declared Content-MD5, without invalidating the URL. GCS stores the supplied content type as object metadata, which takes precedence over the response-content-type that Active Storage sets on download URLs, so an uploaded object could be served as inline HTML under the application's bucket path on storage.googleapis.com. Script in such an object runs on the storage origin rather than the application's, but could register a Service Worker scoped to the bucket path and read or replace a victim's later responses for signed URLs in that bucket. Applications that use the GCS service with cache_control configured and accept direct uploads are affected. GCS services without cache_control sign with V2 and are not affected. This issue is fixed in versions 8.1.4.1 and 8.0.5.2.
Published: 2026-11-10
Score: 4.7 Medium
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

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History

Tue, 10 Nov 2026 21:15:00 +0000

Type Values Removed Values Added
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, when a GCS service is configured with the cache_control option, ActiveStorage::Service::GCSService#url_for_direct_upload signs direct-upload URLs with V4, and the V4 signature covers only the Cache-Control and Host headers. A direct-upload client can therefore send a Content-Type of its choosing, and can omit the declared Content-MD5, without invalidating the URL. GCS stores the supplied content type as object metadata, which takes precedence over the response-content-type that Active Storage sets on download URLs, so an uploaded object could be served as inline HTML under the application's bucket path on storage.googleapis.com. Script in such an object runs on the storage origin rather than the application's, but could register a Service Worker scoped to the bucket path and read or replace a victim's later responses for signed URLs in that bucket. Applications that use the GCS service with cache_control configured and accept direct uploads are affected. GCS services without cache_control sign with V2 and are not affected. This issue is fixed in versions 8.1.4.1 and 8.0.5.2.
Title Active Storage: Unsigned Content-Type in Active Storage GCS direct uploads with cache_control
Weaknesses CWE-345
References
Metrics cvssV3_1

{'score': 4.7, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N'}


Subscriptions

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-11-10T21:11:00.234Z

Reserved: 2026-11-10T17:07:43.285Z

Link: CVE-2026-126084

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-11-10T21:19:27.287

Modified: 2026-11-10T21:19:27.287

Link: CVE-2026-126084

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

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Weaknesses
  • CWE-345

    Insufficient Verification of Data Authenticity