CVE-2021-33564

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.8 under NVD CVSS v3. EPSS exploit probability: 72.2%, top 1% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
Trending — 3 sources updated this weekElevated
9.8
EchelonGraph verdictPatch this weekExploitation is likely or a public exploit exists.
  • High exploitation likelihood — EPSS 72%
CISA-KEV: Not listedEPSS: 72%CVSS: 9.8Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
77(Track*)
EG Risk 77/100SSVC: Track*

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity98% × 45%
Exploitation72% × 40%
Automatability30% × 15%
Action: Watch closely — could escalate to Attend.
EPSS
99.4%
KEV
Not listed

Published

May 29, 2021

Last Modified

November 21, 2024

Advisory Details (6)

Auto-updated Jul 9, 2026
Upstream fix merged — awaiting tagged release. Sources: github_commit.
generic

GitHub - mlr0p/CVE-2021-33564: Argument Injection in Dragonfly Ruby Gem · GitHub

https://github.com/mlr0p/CVE-2021-33564
generic

Security Issue Report · Issue #513 · markevans/dragonfly · GitHub

https://github.com/markevans/dragonfly/issues/513
generic

Comparing v1.3.0...v1.4.0 · markevans/dragonfly · GitHub

https://github.com/markevans/dragonfly/compare/v1.3.0...v1.4.0
github_commit

commit 25399297bb45 (markevans/dragonfly)

Fix landed in markevans/dragonfly commit 25399297bb45 — awaiting tagged release

https://github.com/markevans/dragonfly/commit/25399297bb457f7fcf8e3f91e85945b255b111b5
generic

Redirecting…

https://zxsecurity.co.nz/research/argunment-injection-ruby-dragonfly/
generic
https://raw.githubusercontent.com/projectdiscovery/nuclei-templates/master/cves/2021/CVE-2021-33564.yaml

Affected Packages

(1 across 1 ecosystem)
RubyGems(1)
PackageVulnerable rangeFixed inDependents
dragonfly0.1.0 ... 1.3.0 (80 versions)1.4.0—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 6× in last 7d / 28× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-23 02:01 UTCEG score recompute
  2. 2026-07-22 22:48 UTCEG score recompute
  3. 2026-07-22 14:06 UTCEPSS rescore
  4. 2026-07-22 14:06 UTCEPSS rescore
  5. 2026-07-20 17:05 UTCEPSS rescore
  6. 2026-07-18 19:29 UTCOSV refresh
  7. 2026-07-15 16:55 UTCEPSS rescore
  8. 2026-07-13 22:27 UTCEPSS rescore
  9. 2026-07-13 06:10 UTCEPSS rescore
  10. 2026-07-12 05:44 UTCEPSS rescore
  11. 2026-07-12 05:44 UTCEPSS rescore
  12. 2026-07-09 19:07 UTCEPSS rescore
  13. 2026-07-08 15:12 UTCEPSS rescore
  14. 2026-07-06 16:25 UTCEPSS rescore
  15. 2026-07-06 02:21 UTCEPSS rescore
  16. 2026-07-04 06:29 UTCEPSS rescore
  17. 2026-07-04 06:29 UTCEPSS rescore
  18. 2026-07-01 15:04 UTCEPSS rescore
  19. 2026-07-01 02:18 UTCOSV refresh
  20. 2026-06-28 14:05 UTCEPSS rescore
  21. 2026-06-28 04:54 UTCEPSS rescore
  22. 2026-06-28 04:54 UTCEPSS rescore
  23. 2026-06-25 13:48 UTCEPSS rescore
  24. 2026-06-25 13:48 UTCEPSS rescore
  25. 2026-06-24 14:03 UTCEPSS rescore
Show 26 more
  1. 2026-06-24 14:03 UTCEPSS rescore
  2. 2026-06-23 21:31 UTCEPSS rescore
  3. 2026-06-23 21:31 UTCEPSS rescore
  4. 2026-06-21 14:55 UTCEPSS rescore
  5. 2026-06-21 01:58 UTCEPSS rescore
  6. 2026-06-21 01:58 UTCEPSS rescore
  7. 2026-06-18 17:51 UTCEPSS rescore
  8. 2026-06-18 17:51 UTCEPSS rescore
  9. 2026-06-17 17:51 UTCEPSS rescore
  10. 2026-06-16 17:51 UTCEPSS rescore
  11. 2026-06-16 17:51 UTCEPSS rescore
  12. 2026-06-15 17:46 UTCEPSS rescore
  13. 2026-06-13 22:58 UTCEPSS rescore
  14. 2026-06-13 22:58 UTCEPSS rescore
  15. 2026-06-13 04:43 UTCOSV refresh
  16. 2026-06-08 14:15 UTCEPSS rescore
  17. 2026-06-08 14:15 UTCEPSS rescore
  18. 2026-06-05 22:45 UTCEPSS rescore
  19. 2026-06-05 06:09 UTCEPSS rescore
  20. 2026-06-05 06:09 UTCEPSS rescore
  21. 2026-06-04 13:10 UTCEPSS rescore
  22. 2026-06-04 13:10 UTCEPSS rescore
  23. 2026-05-28 13:43 UTCEPSS rescore
  24. 2026-05-28 13:43 UTCEPSS rescore
  25. 2026-05-26 15:51 UTCEG score recompute
  26. 2026-05-25 09:16 UTCOSV refresh

Publicly available exploits

(2 references)

Working exploit code is in the public domain (1 GitHub PoC). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoCmlr0p/CVE-2021-33564
    First seen May 25, 2021

    Argument Injection in Dragonfly Ruby Gem

    Open source ↗
  • Nucleihttp/cves/2021/CVE-2021-33564.yaml
    First seen Jan 1, 2021

    Ruby Dragonfly <1.4.0 - Remote Code Execution

    Open source ↗

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2021-33564?
CVE-2021-33564 is a critical vulnerability published on May 29, 2021. 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…
When was CVE-2021-33564 disclosed?
CVE-2021-33564 was first published in the National Vulnerability Database on May 29, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-33564 actively exploited?
CVE-2021-33564 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 99.4% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-33564?
CVE-2021-33564 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2021-33564?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-33564, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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