CVE-2026-126084: Rails · Active Storage makes it simple to upload and reference files in cloud services and attach
Affects railsSource GCVE Database
Not known to be exploited · CVSS 4.7 Medium · fixed in 8.1.4.1 : update rails when convenient.
Data as of 13 Nov 2026, 22:23 UTC
Thin evidence
One scorer or none| CNA (GitHub_M) | CVSS 3.1 | 4.7 |
|---|
- Patch
- Available – fixed in 8.1.4.1
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:NExploitation evidence
Disclosed: evidence found.
CVE published 10 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 13 Nov 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.10railspkg:deb/ubuntu/rails?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSrailspkg:deb/ubuntu/rails?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSrailspkg:deb/ubuntu/rails?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu Pro 22.04 LTSrailspkg:deb/ubuntu/rails?arch=source&distro=esm-apps/jammyOther threats | Affected
| Fixed in– |
Ubuntu Pro 20.04 LTSrailspkg:deb/ubuntu/rails?arch=source&distro=esm-apps/focalOther threats | Affected
| Fixed in– |
Ubuntu Pro 18.04 LTSrailspkg:deb/ubuntu/rails?arch=source&distro=esm-apps/bionicOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Upgrade Rails Active Storage to version 8.1.4.1 or 8.0.5.2 or later, where this vulnerability is fixed. Applications using GCS with the cache_control option and accepting direct uploads should apply these updates promptly. GCS services without cache_control configured are not affected. No additional mitigation actions are indicated by the vendor advisory.
Description
A vulnerability in Rails Active Storage affects versions prior to 8.1.4.1 and 8.0.5.2 when using Google Cloud Storage (GCS) with the cache_control option. The issue allows a direct-upload client to specify arbitrary Content-Type headers and omit Content-MD5 without invalidating the signed URL. This can lead to uploaded objects being served with a malicious content type, potentially enabling script execution under the storage.googleapis.com domain and allowing registration of a Service Worker scoped to the bucket path. This vulnerability is fixed in versions 8.1.4.1 and 8.0.5.2.
References
- ubuntu.com/security/CVE-2026-126084 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-126084 (opens in a new tab)
- github.com/rails/rails/security/advisories/GHSA-3w93-6hmw-whh4 (opens in a new tab)
- github.com/rails/rails/commit/8d93f6a872e9550a91bf0e4fce50083a235ef3b1 (opens in a new tab)
- github.com/rails/rails/commit/ddc08ba61a8001e7402864c62e466cf732fc7614 (opens in a new tab)
- github.com/rails/rails/releases/tag/v8.0.5.2 (opens in a new tab)
- github.com/rails/rails/releases/tag/v8.1.4.1 (opens in a new tab)