What is CVE-2026-33173?

CVE-2026-33173 is a medium-severity security vulnerability in activestorage (rubygems), affecting versions >= 8.1.0.beta1, < 8.1.2.1. It is fixed in 8.1.2.1, 8.0.4.1, 7.2.3.1.

Which versions of activestorage are affected by CVE-2026-33173?

activestorage (rubygems) versions >= 8.1.0.beta1, < 8.1.2.1 is affected.

Is there a fix for CVE-2026-33173?

Yes. CVE-2026-33173 is fixed in 8.1.2.1, 8.0.4.1, 7.2.3.1. Upgrade to this version or later.

Is CVE-2026-33173 exploitable, and should I be worried?

Whether CVE-2026-33173 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk.

What actually determines whether CVE-2026-33173 is exploitable, and how bad it is?

Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.

CVE-2026-33173 in activestorage

Q: Which versions of activestorage are affected by CVE-2026-33173?

activestorage (rubygems) versions >= 8.1.0.beta1, < 8.1.2.1 is affected.

Q: Is there a fix for CVE-2026-33173?

Yes. CVE-2026-33173 is fixed in 8.1.2.1, 8.0.4.1, 7.2.3.1. Upgrade to this version or later.

Q: Is CVE-2026-33173 exploitable, and should I be worried?

Whether CVE-2026-33173 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk.

Q: What actually determines whether CVE-2026-33173 is exploitable, and how bad it is?

Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.

Q: How do I fix CVE-2026-33173?

Upgrade: activestorage to 8.1.2.1 or later, activestorage to 8.0.4.1 or later, activestorage to 7.2.3.1 or later.

Summary

Rails Active Storage has possible content type bypass via metadata in direct uploads

Releases

The fixed releases are available at the normal locations.

Credit

This was responsible reported by Hackerone researcher pwnie

Impact

Active Storage's DirectUploadsController accepts arbitrary metadata from the client and persists it on the blob. Because internal flags like identified and analyzed are stored in the same metadata hash, a malicious direct-upload client could set these flags.

Affected versions

activestorage (>= 8.1.0.beta1, < 8.1.2.1) activestorage (>= 8.0.0.beta1, < 8.0.4.1) activestorage (< 7.2.3.1)

Security releases

activestorage → 8.1.2.1 (rubygems) activestorage → 8.0.4.1 (rubygems) activestorage → 7.2.3.1 (rubygems)

Kodem intelligence

Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.

Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.

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Remediation advice

Upgrade the following packages to resolve this vulnerability:

activestorage to 8.1.2.1 or later; activestorage to 8.0.4.1 or later; activestorage to 7.2.3.1 or later

Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.

Frequently Asked Questions

What is CVE-2026-33173? CVE-2026-33173 is a medium-severity security vulnerability in activestorage (rubygems), affecting versions >= 8.1.0.beta1, < 8.1.2.1. It is fixed in 8.1.2.1, 8.0.4.1, 7.2.3.1.
Which versions of activestorage are affected by CVE-2026-33173? activestorage (rubygems) versions >= 8.1.0.beta1, < 8.1.2.1 is affected.
Is there a fix for CVE-2026-33173? Yes. CVE-2026-33173 is fixed in 8.1.2.1, 8.0.4.1, 7.2.3.1. Upgrade to this version or later.
Is CVE-2026-33173 exploitable, and should I be worried? Whether CVE-2026-33173 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
What actually determines whether CVE-2026-33173 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
How do I fix CVE-2026-33173?
- Upgrade activestorage to 8.1.2.1 or later
- Upgrade activestorage to 8.0.4.1 or later
- Upgrade activestorage to 7.2.3.1 or later

Other vulnerabilities in activestorage

CVE-IDSeverityPackage summary

CVE-2026-33658Lowactivestorage: Rails Active Storage has a possible DoS vulnerability in proxy mode via multi-range requests CVE-2026-33202Mediumactivestorage: Rails Active Storage has possible glob injection in its DiskService CVE-2026-33195Highactivestorage: Rails Active Storage has possible Path Traversal in DiskService CVE-2026-33174Mediumactivestorage: Rails Active Storage has a possible DoS vulnerability when in proxy mode via Range requests CVE-2025-24293Criticalactivestorage: Active Storage allowed transformation methods that were potentially unsafe