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Fencer Vulns
high 7.5

CVE-2026-33174 json

Rails Active Storage has a possible DoS vulnerability when in proxy mode via Range requests

published 2026-03-23 7 mo ago modified 2026-09-10 59 d ago also EUVD-2026-14628 , GHSA-r46p-8f7g-vvvg

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 50%
public exploits
0
none known

Summary

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, when serving files through Active Storage's proxy delivery mode, the proxy controller loads the entire requested byte range into memory before sending it. A request with a large or unbounded Range header (e.g. `bytes=0-`) could cause the server to allocate memory proportional to the file size, possibly resulting in a DoS vulnerability through memory exhaustion. Versions 8.1.2.1, 8.0.4.1, and 7.2.3.1 contain a patch.

Patch / fix

  • rubygems activestorage 7.2.3.1, 8.0.4.1, 8.1.2.1
  • rubyonrails rails 7.2.3.1, 8.0.4.1, 8.1.2.1
  • rails Debian 13 2:7.2.2.2+dfsg-2~deb13u2
  • rails Debian 14 2:7.2.3.1+dfsg-1

debian advisories DEBIAN-CVE-2026-33174

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-33174 updated cvss 5.9

Rails: Active Storage: Rails Active Storage: Denial of Service via unbounded Range header

  • Red Hat 3scale API Management Platform 2 3scale-amp21/zync, 3scale-amp22/zync, 3scale-amp24/zync, 3scale-amp25/zync, 3scale-amp26/zync, 3scale-amp20/system, +9 more
    affected: workaround, no fix available, no fix planned “Will not fix”
  • Red Hat 3scale API Management Platform 2 3scale-amp2/zync-rhel9, 3scale-amp2/system-rhel9
    not affected: vulnerable code not present
  • Red Hat Satellite 6 rubygem-activestorage
    not affected: vulnerable code not in execute path

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
7 mo ago

Exploit prediction

0.62% chance of exploitation in the next 30 days, higher than 50% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 6.6 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
CNA 4.0 6.6 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/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 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
rubygems activestorage
>=8.1.0.beta1, <8.1.2.1
>=8.0.0.beta1, <8.0.4.1
<7.2.3.1
8.1.2.1
8.0.4.1
7.2.3.1

Affected products

  • rails activestorage

Classification

Weakness
  • CWE-789 Memory Allocation with Excessive Size Value
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of rails/rails published their own advisory on GitHub. Reviewed sources take precedence over it.