Skip to content
Patch Next
Sign inAdd to your agent

← Actionable
Medium, CVSS 5.3amended

Active Storage: Possible DoS vulnerability in Active Storage proxy mode via storage errors during streaming

CVE-2026-126071GHSA-4v2w-w6g6-f8f8

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (activestorage 8.1.4.1, 8.0.5.2), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

Add to your agent

Affected packages

  • RubyGems activestorage

    Affected
    >= 8.1.0.beta1, < 8.1.4.1>= 8.0.0.beta1, < 8.0.5.2
    Fixed in
    8.0.5.2, 8.1.4.1

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
5.3 · CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS
No dated EPSS signal available.
Source description

As published by the source; long descriptions are shortened.

Impact When Active Storage serves a file through its proxy controllers, `ActiveStorage::Streaming#send_blob_stream` handles an error from the storage service by calling `head` to send a 404 or 500 response. If the error occurs after the first chunk has been written, the response is already committed, and `head` replaces the response body while the server is still reading the original `ActionController::Live` buffer. That buffer is never closed, so the server thread handling the request blocks until the process restarts. Repeated failed downloads could exhaust the server's threads, possibly resulting in a DoS vulnerability. Applications are affected when they store files on a service that streams a download in several requests, such as Amazon S3, an S3-compatible service or Google Cloud Storage, and draw Active Storage's default routes. The proxy routes are drawn whether or not proxy mode is the default for the application. A file deleted while it is being served, or any other…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from osv record GHSA-4v2w-w6g6-f8f8

  2. Revision 1 · created ·

    Published from ghsa record GHSA-4v2w-w6g6-f8f8

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-126071

Advisory: Active Storage: Possible DoS vulnerability in Active Storage proxy mode via storage errors during streaming
IDs: CVE-2026-126071, GHSA-4v2w-w6g6-f8f8
Record: https://patchnext.com/advisories/cve-2026-126071 (revision 2, source checked 11 Nov 2026, 07:35 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: activestorage 8.1.4.1, 8.0.5.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- RubyGems activestorage: affected >= 8.1.0.beta1, < 8.1.4.1; >= 8.0.0.beta1, < 8.0.5.2; fixed in 8.0.5.2, 8.1.4.1

## Suggested inspection (read-only)
- RubyGems activestorage: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on activestorage.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-4v2w-w6g6-f8f8 (GitHub-reviewed advisory GHSA-4v2w-w6g6-f8f8 lists affected ranges: RubyGems activestorage >=8.1.0.beta1 =8.0.0.beta1 <8.0.5.2)
- Verified: https://osv.dev/vulnerability/GHSA-4v2w-w6g6-f8f8 (OSV record GHSA-4v2w-w6g6-f8f8 lists affected ranges: RubyGems activestorage >=8.1.0.beta1 =8.0.0.beta1 <8.0.5.2 (fixed))

Commands are suggestions: review each one before running it.

Loading voting…