How severe is CVE-2021-21305?

CVE-2021-21305 has a CVSS score of 8.8/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2021-21305?

CVE-2021-21305 affects the following packages: carrierwave (RubyGems), carrierwave (RubyGems). Ecosystems affected: RubyGems.

How do I fix CVE-2021-21305?

Update carrierwave to 1.3.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-21305 is resolved across your whole dependency graph.

How do I detect CVE-2021-21305 in my RubyGems dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for carrierwave, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2021-21305 if there is no patch (or I can't update yet)?

Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.

Is CVE-2021-21305 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2021-21305, including 1 in-the-wild exploitation observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2021-21305?

CVE-2021-21305 has an EPSS (Exploit Prediction Scoring System) score of 12.7%, placing it in the 96th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score warrants monitoring and prompt remediation.

What type of vulnerability is CVE-2021-21305?

CVE-2021-21305 is classified as CWE-74 (CWE-74), Code Injection (CWE-94). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2021-21305 published, and has it been updated?

CVE-2021-21305 was published on February 8, 2021 and was last updated on October 20, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

💎

💎 RubyGems

Not in CISA KEV

HIGH severity

CVE-2021-21305 — carrierwave

HIGHFix: carrierwaveuploader/carrierwave@387116f

CVE-2021-21305 is a high-severity (CVSS 8.8) CWE-74 vulnerability in carrierwave. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for carrierwave — see the affected versions and patch details below.

Code Injection vulnerability in CarrierWave::RMagick

Also known asGHSA-cf3w-g86h-35x4

Published

Feb 8, 2021

Updated

Oct 20, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

1 known

Exploitation data as of Oct 30, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

12.7%probability of exploitation in next 30 days

Moderate Risk0.00%

Lower risk than most CVEs96th percentile — riskier than 96% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

2 pkgs affected

💎carrierwave💎carrierwave

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.

Description

Impact

CarrierWave::RMagick has a Code Injection vulnerability. Its #manipulate! method inappropriately evals the content of mutation option(:read/:write), allowing attackers to craft a string that can be executed as a Ruby code. If an application developer supplies untrusted inputs to the option, it will lead to remote code execution(RCE).

(But supplying untrusted input to the option itself is dangerous even in absence of this vulnerability, since is prone to DoS vulnerability - attackers can try to consume massive amounts of memory by resizing to a very large dimension)

Proof of Concept

class MyUploader < CarrierWave::Uploader::Base
  include CarrierWave::RMagick
end

MyUploader.new.manipulate!({ read: { density: "1 }; p 'Hacked'; {" }}) # => shows "Hacked"

Patches

Upgrade to 2.1.1 or 1.3.2.

Workarounds

Stop supplying untrusted input to #manipulate!'s mutation option.

References

Code Injection Software Attack

For more information

If you have any questions or comments about this advisory:

Open an issue in CarrierWave repo
Email me at [email protected]

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
💎RubyGems	`carrierwave`	all versions	1.3.2`bundle update carrierwave --conservative`
💎RubyGems	`carrierwave`	≥ 2.0.0&&< 2.1.1	2.1.1`bundle update carrierwave --conservative`

Affected Products

1 product · 2 configurations

Application

carrierwavecarrierwave_project

≥ 2.0.1 && < 2.1.1

range

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

CarrierWave is an open-source RubyGem which provides a simple and flexib…

github.comNVDFeb 2021

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for carrierwave, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update carrierwave to 1.3.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-21305 is resolved across your whole dependency graph.
Workarounds
Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

UbuntuHIGH

USN-7497-1Ubuntu

Frequently Asked Questions

### Impact [CarrierWave::RMagick](https://github.com/carrierwaveuploader/carrierwave/blob/master/lib/carrierwave/processing/rmagick.rb) has a Code Injection vulnerability. Its `#manipulate!` method inappropriately evals the content of mutation option(`:read`/`:write`), allowing attackers to craft a string that can be executed as a Ruby code. If an application developer supplies untrusted inputs to the option, it will lead to remote code execution(RCE). (But supplying untrusted input to the option itself is dangerous even in absence of this vulnerability, since is prone to DoS vulnerability -