VulnerabilityPublished 12 Nov 2026

CVE-2026-122006: Active Storage · Possible arbitrary file write and read in image analysis

Affects activestorageSource GCVE Database

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Authoritative record:CVE-2026-122006· Critical 9.8

Not known to be exploited · CVSS 9.8 Critical : upgrade to 8.1.4.1 as a priority.

Data as of 13 Nov 2026, 00:06 UTC

CVSS 3.1 base score

9.8Critical

How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none

CVSS scores by source
CNA (mitre)	CVSS 3.1	9.8

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:H/I:H/A:H

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 4 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 12 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade activestorage to 8.1.4.1; activestorage to 8.0.5.2.

Affected software

Product	Affected	Fixed in
RubyGemsactivestorage	Affected >=8.1.0.beta1 <8.1.4.1	Fixed in 8.1.4.1
RubyGemsactivestorage	Affected <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.

Description

### Impact A Rails application that processes attachments with ImageMagick may allow an unauthenticated attacker to write arbitrary files on the server and, when attachments are stored with the Disk service, to read arbitrary files readable by the application process. Those files typically include `secret_key_base` and credentials for external systems, which may in turn allow escalation to remote code execution or lateral movement to those systems. ### Details ImageMagick selects a coder from the content of the file it is given, and some coders act on files named inside the image rather than on the image itself. Active Storage constrained none of ImageMagick's coders, and the ImageMagick analyzer runs when a file is attached, so an attacker who can upload a crafted file may be able to invoke one. Attaching the upload is sufficient; no variant, preview, or `analyze` call is required. One specific attack chain has been reported to us, but we do not assume it is the only one that exists. The fixed versions ship an ImageMagick security policy and prepend its directory to `MAGICK_CONFIGURE_PATH` through `MiniMagick.cli_env`, so every ImageMagick process that MiniMagick spawns applies it. The policy denies the `MSL` scripting coder, the coders that read or delete files other than the image, fetch remote or local references, or display to a screen, every coder backed by Ghostscript together with the `gs` delegate, and `@filename` indirection. ImageMagick applies every `policy.xml` on its search path, so the shipped policy adds to the host's policy rather than replacing it. The policy applies to every ImageMagick command that MiniMagick runs, not only those of Active Storage. See the `activestorage` CHANGELOG and "ImageMagick Security Policy" in the Active Storage guide. ### Affected applications An application is affected if it meets all of these requirements: - Uses ImageMagick for Active Storage image processing. This is `config.active_storage.variant_processor = :mini_magick`, which is the default for applications on `load_defaults 6.1` or earlier. - Runs ImageMagick under a security policy that does not already deny the coders involved. The policies that Debian and Ubuntu package do not. - Allows file uploads from untrusted users. ### Mitigation - Upgrade to a fixed version of `activestorage`. - An application whose variant processor is `:mini_magick` must use mini_magick `>= 5.1`, which applying the policy requires. With an older mini_magick, such an application raises an exception during boot. - An application that renders PostScript or PDF through ImageMagick must re-allow the `gs` delegate and the coders it uses in the host's `policy.xml`. - An application that replaces `MiniMagick.cli_env` after boot, clears the environment with `MiniMagick.cli_prefix`, or installs its own `MiniMagick::Shell` does not receive the shipped policy and must carry its rules in ImageMagick's system policy. GraphicsMagick does not read ImageMagick policies. - If attachments are stored with the Disk service, change `secret_key_base` and every secret readable by the application process, including the master key and everything `config/credentials.yml.enc` holds, storage and database credentials, and third-party tokens. Do not retain an exposed secret as a fallback. ### Workarounds Copy the rules of the policy that the fixed versions ship, `activestorage/lib/active_storage/image_magick/policy.xml`, into ImageMagick's system policy, for example `/etc/ImageMagick-7/policy.xml`. At a minimum, deny the `MSL` coder, the Ghostscript coders, and the `gs` delegate: ```xml <policy domain="coder" rights="none" pattern="MSL"/> <policy domain="delegate" rights="none" pattern="gs"/> <policy domain="coder" rights="none" pattern="{PS,PS2,PS3,EPS,EPS2,EPS3,EPI,EPSF,EPSI,EPT,EPT2,EPT3,PDF,AI,EPDF,PDFA,POCKETMOD,XPS,PCL}"/> ``` ### Releases The fixed releases are available at the normal locations. Patches for those who cannot upgrade at once: - 8.1: https://github.com/rails/rails/commit/468aa9a93fc98f5476b6821770f4ccfcb7f7d328 - 8.0: https://github.com/rails/rails/commit/ea8c40121ce53a3d0255cd4eb6d13bfe3bc01776 ### Versions affected - activestorage < 8.0.5.2 - activestorage >= 8.1, < 8.1.4.1 ### Credit This issue was responsibly reported by HackerOne researcher [ryotak](https://hackerone.com/ryotak). ### References - ImageMagick [security policy](https://imagemagick.org/security-policy/)

CWE-1188Initialization of a Resource with an Insecure Default (opens in a new tab)
Base weakness
The product initializes or sets a resource with a default that is intended to be changed by the product's installer, administrator, or maintainer, but the default is not secure.
OWASP Cheat Sheets
Forgot Password (opens in a new tab)
OWASP ASVS 4.0.3
V2.3.1 (opens in a new tab)
V2.6.2 (opens in a new tab)
V2.7.6 (opens in a new tab)
Attack patterns
Exploitation of Thunderbolt Protection Flaws (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

Public exploits and detectionGitHub proofs of concept

WeaknessesCWE-1188

Technical details

References

Community reviews

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