CVE-2026-33658: Activestorage Denial of Service Vulnerability

LOW
Advisory Identifier: GHSA-p9fm-f462-ggrg
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CVSS 6.5
CWE-770
Published
Advisory Summary

CVE-2026-33658 is a LOW (CVSS 6.5) denial of service vulnerability (CWE-770: Allocation of Resources Without Limits or Throttling) affecting Activestorage libraries in the RubyGems ecosystem. The issue involves rails active storage has a possible dos vulnerability in proxy mode via multi-range requests. Remediation is available by upgrading affected packages to version 8.1.2.1, 8.0.4.1, 7.2.3.1.

CVE-2026-33658 at a Glance

CVE Identifier CVE-2026-33658
GHSA Identifier GHSA-p9fm-f462-ggrg
Severity LOW
CVSS v3.1 Base Score 6.5
CWE Classification CWE-770: Allocation of Resources Without Limits or Throttling
Affected Product Activestorage
Package Ecosystem RubyGems
Published Date
Last Updated

Security Impact

CVSS: 6.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability High (A:H)

How to Fix CVE-2026-33658

To remediate this vulnerability, upgrade all affected Activestorage dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

activestorage fixed: 8.1.2.1 
Upgrade activestorage to 8.1.2.1
activestorage fixed: 8.0.4.1 
Upgrade activestorage to 8.0.4.1
activestorage fixed: 7.2.3.1 
Upgrade activestorage to 7.2.3.1
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for activestorage

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-33658, inspect your project dependencies for Activestorage:

inspect dependencies for activestorage

Analyze the terminal output to locate any version of Activestorage in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 8.1.2.1), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-770: Allocation of Resources Without Limits or Throttling, where the product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated. In Activestorage, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact Active Storage's proxy controller does not limit the number of byte ranges in an HTTP Range header. A request with thousands of small ranges causes disproportionate CPU usage compared to a normal request for the same file, possibly resulting in a DoS vulnerability. ### Releases The fixed releases are available at the normal locations. ### Credit This issue was responsibly reported by Hackerone researcher [thwin_htet](https://hackerone.com/thwin_htet).

CVE-2026-33658 Affected Activestorage Versions

3 component(s)
Fixed Versions:
8.1.2.18.0.4.17.2.3.1
Product / Package Ecosystem Affected Versions Fixed Version
activestorage
gem/activestorage
RubyGems
≥ 8.1.0
< 8.1.2.1
8.1.2.1
activestorage
gem/activestorage
RubyGems
≥ 8.0.0
< 8.0.4.1
8.0.4.1
activestorage
gem/activestorage
RubyGems
< 7.2.3.1
7.2.3.1

References

GitHub Advisory / Wiki ADVISORY
https://github.com/rails/rails/security/advisories/GHSA-p9fm-f462-ggrg
NVD — CVE-2026-33658 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-33658
Activestorage Source Repository REPOSITORY
https://github.com/rails/rails
Activestorage Release RELEASE
https://github.com/rails/rails/releases/tag/v7.2.3.1
Activestorage Release RELEASE
https://github.com/rails/rails/releases/tag/v8.0.4.1
Activestorage Release RELEASE
https://github.com/rails/rails/releases/tag/v8.1.2.1
Activestorage Source Repository REPOSITORY
https://github.com/rubysec/ruby-advisory-db/blob/master/gems/activestorage/CVE-2026-33658.yml

Frequently Asked Questions

What is CVE-2026-33658?
CVE-2026-33658 is a security vulnerability in Activestorage involving Rails Active Storage has a possible DoS vulnerability in proxy mode via multi-range requests under CWE-770: Allocation of Resources Without Limits or Throttling.
Which Activestorage versions are affected?
Affected versions include releases prior to 8.1.2.1, 8.0.4.1, 7.2.3.1 across affected packages: activestorage.
What version fixes CVE-2026-33658?
Upgrading to 8.1.2.1, 8.0.4.1, 7.2.3.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is activestorage affected?
Yes, activestorage is affected in releases prior to 8.1.2.1, 8.0.4.1, 7.2.3.1. Upgrade your dependency to 8.1.2.1, 8.0.4.1, 7.2.3.1 or later.
What is the CVSS score of CVE-2026-33658?
CVE-2026-33658 has a CVSS v3.1 base score of 6.5 (LOW) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2026-33658?
CVE-2026-33658 is classified under CWE-770: Allocation of Resources Without Limits or Throttling (The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.).
How can I check RubyGems dependencies for CVE-2026-33658?
Run the dependency tree command: 'inspect dependencies for activestorage'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-p9fm-f462-ggrg",
  "modified" : "2026-05-06T21:23:02Z",
  "published" : "2026-03-25T21:04:50Z",
  "aliases" : [ "CVE-2026-33658" ],
  "summary" : "Rails Active Storage has a possible DoS vulnerability in proxy mode via multi-range requests",
  "details" : "### Impact\nActive Storage's proxy controller does not limit the number of byte ranges in an HTTP Range header. A request with thousands of small ranges causes disproportionate CPU usage compared to a normal request for the same file, possibly resulting in a DoS vulnerability.\n\n### Releases\nThe fixed releases are available at the normal locations.\n\n### Credit\nThis issue was responsibly reported by Hackerone researcher [thwin_htet](https://hackerone.com/thwin_htet).",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "RubyGems",
      "name" : "activestorage"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "8.1.0"
      }, {
        "fixed" : "8.1.2.1"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "RubyGems",
      "name" : "activestorage"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "8.0.0"
      }, {
        "fixed" : "8.0.4.1"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "RubyGems",
      "name" : "activestorage"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "7.2.3.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/rails/rails/security/advisories/GHSA-p9fm-f462-ggrg"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-33658"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/rails/rails"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rails/rails/releases/tag/v7.2.3.1"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rails/rails/releases/tag/v8.0.4.1"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rails/rails/releases/tag/v8.1.2.1"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/activestorage/CVE-2026-33658.yml"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-770" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-25T21:04:50Z",
    "nvd_published_at" : "2026-03-26T22:16:29Z"
  }
}