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CVE.org (no NVD analysis yet)· CNA GitHub_M

CVE-2026-126186: Active Storage: Possible arbitrary file read and remote code execution in Active Storage video previews, analysis and image processing

HighCVSS 8.8 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 35/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.51% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: activestorage (RubyGems) 8.1.4.1, 8.0.5.2.

Low priority for now. Upgrade to activestorage (RubyGems) 8.1.4.1, 8.0.5.2 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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, ActiveStorage::Blob#open writes a blob to a tempfile whose name carries the extension of the uploaded filename, and hands that path to ffprobe (VideoAnalyzer, AudioAnalyzer), ffmpeg (VideoPreviewer) and ImageMagick (ImageAnalyzer, the :mini_magick variant processor). These tools select a decoder from the file extension when the content does not identify its own format, so an attacker who chooses the filename and declares the content type of an upload chooses which decoder processes it. An FFmpeg built with AviSynth support treats a file with the .avs extension as an AviSynth script and evaluates it, which could disclose files readable by the application process through the preview image, or load a native library the attacker has also uploaded, possibly leading to remote code execution in the FFmpeg process. ImageMagick selects its coders and delegates from the extension in the same way. An application is affected if it accepts uploads from untrusted users and analyzes video or audio attachments, generates video previews, or processes images with ImageMagick. The AviSynth attack additionally requires an FFmpeg built with --enable-avisynth and the AviSynthPlus runtime on the host. Upstream FFmpeg and the common Linux distribution and Homebrew packages do not enable it; the GPL builds distributed for Windows and Linux from ffmpeg.org do. Other decoders that FFmpeg or ImageMagick select from the extension may be reachable without AviSynth. This issue is fixed in versions 8.1.4.1 and 8.0.5.2.

Published
Nov 10, 2026
Updated
Nov 12, 2026
EPSS
0.5% · 44th percentile

Report tools

JSON

Action score

35

Monitor

Low priority for now.

CVSS
35 / 40 · 8.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.5%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · GitHub_M
8.8
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

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  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • rails rails

    • >= 8.1, < 8.1.4.1, < 8.0.5.2affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12railsfrom 0—
RubyGemsactivestoragefrom 8.1.0.beta1 · before 8.1.4.18.1.4.1
RubyGemsactivestoragebefore 8.0.5.28.0.5.2

Same product

rails: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-66066Action Pack: Possible arbitrary file read and remote code execution in Active Storage variant processing
    60This week
  • CVE-2026-126081Action Pack: Possible Strong Parameters bypass in Parameters#each_key
    30Monitor
  • CVE-2026-126080Active Support: Possible DoS vulnerability in Active Support safe_constantize
    30Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2026-126084Nov 10, 2026 · Active Storage: Unsigned Content-Type in Active Storage GCS direct uploads with cache_control
    18Monitor
  • ← EarlierCVE-2026-126085Nov 10, 2026 · Active Storage: Possible circumvention of file size limits in Active Storage direct uploads to Google Cloud Storage
    21Monitor
  • Later →CVE-2026-126188Nov 11, 2026 · Active Storage: Possible local file disclosure in Active Storage video previews and analysis
    14Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
RubyGems:activestorage8.0.5.2Package registry (OSV)
RubyGems:activestorage8.1.4.1Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. Published
  2. Fix recordedsame day
  3. TodayNov 13, 2026+2 d
EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

  • CVE-2026-1260680 days apartAction Mailbox: Possible signature replay in Action Mailbox Mailgun ingress
    14Monitor

Bug bounty scope

The product’s vendor appears in a public program. Matched by name; verify the scope text in the program.

Not on record for this CVE: researcher credit.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-646 · Reliance on File Name or Extension of Externally-Supplied File

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. SSVC exploitation— → none
  2. Fix✗ → ✓
  3. Exploit maturity— → none

For records you follow, these changes also arrive as notifications. →

References

Show all references (4 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records