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TI-2026-27073 Aliases CVE-2026-34829GHSA-8vqr-qjwx-82mw

Rack: Denial of Service via Unbounded Multipart File Upload Without Content-Length

Priority LOW 39CWE-400Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Partial Red Hat: 2 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-400.

Summary

Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Multipart::Parser only wraps the request body in a BoundedIO when CONTENT_LENGTH is present. When a multipart/form-data request is sent without a Content-Length header, such as with HTTP chunked transfer encoding, multipart parsing continues until end-of-stream with no total size limit. For file parts, the uploaded body is written directly to a temporary file on disk rather than being constrained by the buffered in-memory upload limit. An unauthenticated attacker can therefore stream an arbitrarily large multipart file upload and consume unbounded disk space. This results in a denial of service condition for Rack applications that accept multipart form data. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00375 31st percentileScored 2026-11-07
Fix Partial rack (rack): 2.2.23, 3.1.21, 3.2.6rack (RubyGems): 2.2.23, 3.1.21, 3.2.6Red Hat: 2 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
rackrackbefore 2.2.23; 3.0.0.beta1 to before 3.1.21; 3.2.0 to before 3.2.62.2.23, 3.1.21, 3.2.6Patch availableCNA
—rack (RubyGems)before 2.2.232.2.23Patch availableGHSA-8vqr-qjwx-82mw
—rack (RubyGems)3.0.0.beta1 to before 3.1.213.1.21Patch availableGHSA-8vqr-qjwx-82mw
—rack (RubyGems)3.2.0 to before 3.2.63.2.6Patch availableGHSA-8vqr-qjwx-82mw
  • rack Vendorrack Affected before 2.2.23; 3.0.0.beta1 to before 3.1.21; 3.2.0 to before 3.2.6 Fixed in 2.2.23, 3.1.21, 3.2.6 Patch available CNA
  • rack (RubyGems) Vendor— Affected before 2.2.23 Fixed in 2.2.23 Patch available GHSA-8vqr-qjwx-82mw
  • rack (RubyGems) Vendor— Affected 3.0.0.beta1 to before 3.1.21 Fixed in 3.1.21 Patch available GHSA-8vqr-qjwx-82mw
  • rack (RubyGems) Vendor— Affected 3.2.0 to before 3.2.6 Fixed in 3.2.6 Patch available GHSA-8vqr-qjwx-82mw

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:rack:rack:*:*:*:*:*:ruby:*:*before 2.2.23; 3.0.0 to before 3.1.21; 3.2.0 to before 3.2.6Vulnerablerack
  • cpe:2.3:a:rack:rack:*:*:*:*:*:ruby:*:* Versions before 2.2.23; 3.0.0 to before 3.1.21; 3.2.0 to before 3.2.6 Vulnerable ·rack

Remediation

  • Fix · CNA rack (rack) Fixed in 2.2.23, 3.1.21, 3.2.6
  • Fix · GHSA-8vqr-qjwx-82mw rack (RubyGems) Fixed in 2.2.23 Advisory →
  • Fix · GHSA-8vqr-qjwx-82mw rack (RubyGems) Fixed in 3.1.21 Advisory →
  • Fix · GHSA-8vqr-qjwx-82mw rack (RubyGems) Fixed in 3.2.6 Advisory →

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

ProductStatusPlan or fix
Logging Subsystem for Red Hat OpenShiftAffectedNo fix yet
Red Hat 3scale API Management Platform 2AffectedNo fix yet
Not affected: 4 products
  • Red Hat Enterprise Linux 10
  • Red Hat Enterprise Linux 7
  • Red Hat Enterprise Linux 8
  • Red Hat Enterprise Linux 9

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-34829
  2. 2026-10-03 Alias added: GHSA-8vqr-qjwx-82mw
  3. 2026-10-11 EPSS moved to the 50th–90th percentile
  4. 2026-10-25 EPSS moved to the below the 50th percentile
  5. 2026-10-25 Priority changed: MEDIUM → LOW

References

Advisory 2

Other 2

  • TI-2024-16580 Rack ReDos in content type parsing (2nd degree polynomial) CVSS 3.1HIGH 7.5
  • TI-2024-17236 Possible Denial of Service Vulnerability in Rack Header Parsing CVSS 3.1HIGH 7.5
  • TI-2024-17231 Possible DoS Vulnerability with Range Header in Rack CVSS 3.1HIGH 7.5
  • TI-2023-12254 Uncontrolled resource consumption in https://github.com/rack/rack CVSS 3.1HIGH 7.5
  • TI-2025-38165 Rack's multipart parser buffers unbounded per-part headers, enabling DoS (memory exhaustion) CVSS 3.1HIGH 7.5
  • TI-2025-38163 Rack's unbounded multipart preamble buffering enables DoS (memory exhaustion) CVSS 3.1HIGH 7.5
See all 36 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences