CVSS 3.1
5.3 mediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:HCVE-2026-126071 Active Storage: Possible DoS vulnerability in Active Storage proxy mode via storage errors during streaming
Medium (5.3) in rails rails. EPSS 0.4% estimated probability of exploitation activity in the next 30 days. Fixed in activestorage 8.0.5.2, 8.1.4.1.
On this page
Active Storage makes it simple to upload and reference files in cloud services and attach those files to Active Record objects. From 8.0 until 8.0.5.2 and 8.1.4.1, 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 storage error partway through a download, triggers the condition. This issue is fixed in versions 8.1.4.1 and 8.0.5.2.
Severity
- EPSS
- 0.4% estimated probability of exploitation activity in the next 30 days; 39th percentile. Scored 2026-11-13. A forecast for this CVE across the internet, not for your own systems.
- CISA's assessment (SSVC)
- Exploitation: none · Automatable: no · Technical impact: partial, assessed 2026-11-13. From CISA's Vulnrichment in the CVE List: whether it is exploited, whether exploiting it can be automated, and how much control it gives.
- CWE
- CWE-772 Missing Release of Resource after Effective Lifetime
- Published
- Modified
- Assigned by
- GitHub_M (CNA)
- NVD analysis
- Awaiting analysis
- Record from
- the NVD, synced
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Affected
Versions
From the CNA's record in the CVE List.
| Product | Affected |
|---|---|
| rails | >= 8.1, < 8.1.4.1 |
| rails | >= 8.0, < 8.0.5.2 |
Fix and patched versions
activestorage(RubyGems): fixed in 8.1.4.1, 8.0.5.2
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-4v2w-w6g6-f8f8 | RubyGems | activestorage | >=8.1.0.beta1 <8.1.4.1 | 8.1.4.1 |
| GHSA-4v2w-w6g6-f8f8 | RubyGems | activestorage | >=8.0.0.beta1 <8.0.5.2 | 8.0.5.2 |
Linux distributions
| Distribution | Release | Package | Fixed in | Advisory |
|---|---|---|---|---|
| Ubuntu | 24.04:LTS, 26.04:LTS, 26.10 and 4 more | rails | no fix listed | UBUNTU-CVE-2026-126071 |
From the distributions' data via OSV.dev: Ubuntu Security Notices © Canonical Ltd., CC BY-SA 4.0. Modified: reformatted and linked to CVE records. Credits. On the distributions' own pages: Ubuntu.
Attack patterns (CAPEC)
- CAPEC-469 HTTP DoS Severity: Low
The attack patterns MITRE's CAPEC relates to this record's weaknesses, as MITRE names them. Credits.
References
- https://github.com/rails/rails/commit/3c67a693fb21870ecb1222e3da59d5c491a62009
- https://github.com/rails/rails/commit/655b4442de136a3701334607f634d698bf9d5b82
- https://github.com/rails/rails/releases/tag/v8.0.5.2
- https://github.com/rails/rails/releases/tag/v8.1.4.1
- https://github.com/rails/rails/security/advisories/GHSA-4v2w-w6g6-f8f8