CVE-2021-33564

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 72.1% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2021-05-29 · updated 2026-06-17
Weakness: CWE-88

Description

An argument injection vulnerability in the Dragonfly gem before 1.4.0 for Ruby allows remote attackers to read and write to arbitrary files via a crafted URL when the verify_url option is disabled. This may lead to code execution. The problem occurs because the generate and process features mishandle use of the ImageMagick convert utility.

Affected products

Dragonfly Project Dragonfly: before 1.4.0 — fixed in 1.4.0

How to fix

Upgrade to a fixed version: Dragonfly Project Dragonfly 1.4.0. Check the vendor advisory for mitigations.

References

https://github.com/markevans/dragonfly/commit/25399297bb457f7fcf8e3f91e85945b255b111b5
https://github.com/markevans/dragonfly/compare/v1.3.0...v1.4.0
https://github.com/markevans/dragonfly/issues/513
https://github.com/mlr0p/CVE-2021-33564
https://raw.githubusercontent.com/projectdiscovery/nuclei-templates/master/cves/2021/CVE-2021-33564.yaml
https://zxsecurity.co.nz/research/argunment-injection-ruby-dragonfly/
https://github.com/markevans/dragonfly/commit/25399297bb457f7fcf8e3f91e85945b255b111b5
https://github.com/markevans/dragonfly/compare/v1.3.0...v1.4.0
https://github.com/markevans/dragonfly/issues/513
https://github.com/mlr0p/CVE-2021-33564
https://raw.githubusercontent.com/projectdiscovery/nuclei-templates/master/cves/2021/CVE-2021-33564.yaml
https://zxsecurity.co.nz/research/argunment-injection-ruby-dragonfly/

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