Rails Active Storage has a possible DoS vulnerability in proxy mode via multi-range requests
Active Storage allows users to attach cloud and local files in Rails applications. Prior to versions 8.1.2.1, 8.0.4.1, and 7.2.3.1 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. Versions 8.1.2.1, 8.0.4.1, and 7.2.3.1 contain a patch.
- Published
- Mar 26, 2026
- Updated
- Jun 17, 2026
- EPSS
- 0.6% · 45th percentile
- CWE
- CWE-770
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Report tools
Action score
9
Monitor
Low priority for now.
- CVSS
- 9 / 40 · 2.3 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.6%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- —
- CNA · GitHub_M
- 2.3
- NVD has not scored this yet; the score shown is the CNA’s.
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
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| rubyonrails | rails | cpe:2.3:a:rubyonrails:rails |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- rubyonrails railsbefore 7.2.3.1
- rubyonrails rails8.0.0 and later · before 8.0.4.1
- rubyonrails rails8.1.0 and later · before 8.1.2.1
Versions reported by the vendor
Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.
rails activestorage
- >= 8.1.0, < 8.1.2.1, >= 8.0.0, < 8.0.4.1, < 7.2.3.1affected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | rails | all versions | — |
| Debian:14 | rails | before 2:7.2.3.1+dfsg-1 | 2:7.2.3.1+dfsg-1 |
| RubyGems | activestorage | from 8.0.0 · before 8.0.4.1 | 8.0.4.1 |
| RubyGems | activestorage | from 8.1.0 · before 8.1.2.1 | 8.1.2.1 |
| RubyGems | activestorage | before 7.2.3.1 | 7.2.3.1 |
Same product
rubyonrails: all recordsOther highest-scoring records for the same primary product.
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Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| debian:rails | 2:7.2.3.1+dfsg-1 · Debian:14 | Package registry (OSV) |
| RubyGems:activestorage | 7.2.3.1 | Package registry (OSV) |
| RubyGems:activestorage | 8.0.4.1 | Package registry (OSV) |
| RubyGems:activestorage | 8.1.2.1 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
The product’s vendor appears in a public program. Matched by name; verify the scope text in the program.
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- A low-privileged account is enough.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- Integrity
- Availability
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- X
Weakness class (CWE)
CWE-770 · Allocation of Resources Without Limits or ThrottlingCVSS vector
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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
nvd-secondary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
- FloodingCAPEC-125likelihood: High · Medium
- Excessive AllocationCAPEC-130likelihood: Medium · Medium
- XML Ping of the DeathCAPEC-147likelihood: Low · Medium
- Exponential Data ExpansionCAPEC-197likelihood: High · Medium
- Serialized Data Parameter BlowupCAPEC-229likelihood: High · High
- Serialized Data with Nested PayloadsCAPEC-230likelihood: Medium · High
- Oversized Serialized Data PayloadsCAPEC-231likelihood: Medium · High
- HTTP DoSCAPEC-469Low
ATT&CK techniques
- Network Denial of Service:Direct Network FloodT1498.001
- Network Denial of Service:Reflection AmplificationT1498.002
- Endpoint Denial of ServiceT1499
- Endpoint Denial of Service: OS Exhaustion FloodT1499.001
- Endpoint Denial of Service:Service Exhaustion FloodT1499.002
- Endpoint Denial of Service:Application Exhaustion FloodT1499.003
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
- Fix✗ → ✓
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References
- github.com/rails/rails/releases/tag/v7.2.3.1
- github.com/rails/rails/releases/tag/v8.0.4.1
- github.com/rails/rails/releases/tag/v8.1.2.1
- github.com/rails/rails/security/advisories/GHSA-p9fm-f462-ggrg
- github.com/rubysec/ruby-advisory-db/blob/master/gems/activestorage/CVE-2026-33658.yml
Vendor advisories and official records. Exploit/PoC links are deliberately left out.