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CVE-2026-126085VulnerabilityPublished

activestorage · Active Storage: Possible circumvention of file size limits in Active Storage direct uploads to Google Cloud Storage

Affects activestorageSource GCVE Database

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Mentioned vulnerabilities

Authoritative record:CVE-2026-126085· Medium 5.3

Not known to be exploited · CVSS 5.3 Medium : upgrade to 8.1.4.1 when convenient.

Data as of 10 Nov 2026, 22:36 UTC

CVSS 3.1 base score
5.3Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (GitHub_M)CVSS 3.15.3
Patch
Available – fixed in 8.1.4.1, 8.0.5.2
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 10 Nov 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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 10 Nov 2026.

What to do

Upgrade activestorage to 8.1.4.1; activestorage to 8.0.5.2.

Affected software

ProductAffectedFixed in
RubyGemsactivestorageAffected
  • >=8.1.0.beta1 <8.1.4.1
Fixed in
  • 8.1.4.1
RubyGemsactivestorageAffected
  • <8.0.5.2
Fixed in
  • 8.0.5.2

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade to Active Storage versions 8.1.4.1 or 8.0.5.2 or later where the issue is fixed. For those unable to upgrade immediately, apply the provided patches for versions 8.1 and 8.0. Additionally, update the Google Cloud Storage bucket CORS configuration to include 'x-goog-content-length-range' in the 'responseHeader' list to ensure browser direct uploads function correctly after the upgrade. No other mitigation is required as the fix enforces size constraints server-side.

Description

Active Storage's Google Cloud Storage direct upload feature did not enforce file size limits properly, allowing clients to upload files larger than the declared size. This could bypass application-level file size validations and quotas. The issue was fixed by signing an 'x-goog-content-length-range' header that enforces the declared size, with fixed versions released.

References

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