CVE-2026-33174Network attack vector

Memory exhaustion via unbounded proxy byte ranges

Published Mar 23, 2026 · Updated Mar 23, 2026

Denial of service in affected Rails Active Storage 7.2, 8.0, and 8.1 releases allows remote attackers to exhaust application memory. Blobs::ProxyController reads the entire requested byte range into memory before responding, without limiting the aggregate range size. Exposure requires an attacker-accessible blob served through proxy delivery mode; a large or open-ended Range request can interrupt the application process as memory is exhausted.

CVSS severityUnavailable
Unscored
EPSS probability0.61%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in affected Rails Active Storage 7.2, 8.0, and 8.1 releases allows remote attackers to exhaust application memory. Blobs::ProxyController reads the entire requested byte range into memory before responding, without limiting the aggregate range size. Exposure requires an attacker-accessible blob served through proxy delivery mode; a large or open-ended Range request can interrupt the application process as memory is exhausted.

The record

CVE
CVE-2026-33174
Published
Mar 23, 2026
Updated
Mar 23, 2026
Vendor
Rails
Product
Active Storage
Classifications
CWE-789, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 23, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 23, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 7.2.3.1
  2. Affected versionversion=>= 8.0.0.beta1, < 8.0.4.1
  3. Affected versionversion=>= 8.1.0.beta1, < 8.1.2.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Rails · Active Storageversion=< 7.2.3.1; version=>= 8.0.0.beta1, < 8.0.4.1; version=>= 8.1.0.beta1, < 8.1.2.1

Published CVSS scores

6.6GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-789Memory Allocation with Excessive Size Value
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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