TI-2026-21447 Aliases CVE-2026-26962 GHSA-rx22-g9mx-qrhv

Rack: Header injection in multipart requests

LOW 28CWE-93Published 2026-04-02 · Updated 2026-04-03

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Impact type: —
Confidentiality · integrity · availability: Low · Low · None
Fix status: Partial Red Hat: 6 without a fix

Attack profile from CVSS 3.1 · NVD. Fix status from CNA, GitHub and Red Hat.

Summary

Rack is a modular Ruby web server interface. From version 3.2.0 to before version 3.2.6, Rack::Multipart::Parser unfolds folded multipart part headers incorrectly. When a multipart header contains an obs-fold sequence, Rack preserves the embedded CRLF in parsed parameter values such as filename or name instead of removing the folded line break during unfolding. As a result, applications that later reuse those parsed values in HTTP response headers may be vulnerable to downstream header injection or response splitting. This issue has been patched in version 3.2.6.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00235 14th percentileScored 2026-11-07

Fix Partial rack (rack): 3.2.6rack (RubyGems): 3.2.6Red Hat: 6 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Partial

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

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
rack	rack	3.2.0 to before 3.2.6	3.2.6	Patch available	CNA
—	rack (RubyGems)	3.2.0 to before 3.2.6	3.2.6	Patch available	GHSA-rx22-g9mx-qrhv

rack Vendorrack Affected 3.2.0 to before 3.2.6 Fixed in 3.2.6 Patch available CNA
rack (RubyGems) Vendor— Affected 3.2.0 to before 3.2.6 Fixed in 3.2.6 Patch available GHSA-rx22-g9mx-qrhv

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:rack:rack::::::ruby::*	3.2.0 to before 3.2.6	Vulnerable	rack

cpe:2.3:a:rack:rack:*:*:*:*:*:ruby:*:* Versions 3.2.0 to before 3.2.6 Vulnerable ·rack

Remediation

Fix · CNA rack (rack) Fixed in 3.2.6
Fix · GHSA-rx22-g9mx-qrhv rack (RubyGems) Fixed in 3.2.6 Advisory →

Vendor assessments

Red Hat

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

Product	Status	Plan or fix
Logging Subsystem for Red Hat OpenShift	Affected	No fix yet: Fix deferred
Red Hat 3scale API Management Platform 2	Affected	No fix yet: Fix deferred
Red Hat Enterprise Linux 10	Affected	No fix yet: Fix deferred
Red Hat Enterprise Linux 7	Affected	No fix yet: Fix deferred
Red Hat Enterprise Linux 8	Affected	No fix yet: Fix deferred
Red Hat Enterprise Linux 9	Affected	No fix yet: Fix deferred

Timeline

2026-10-02 Threatist record created from CVE-2026-26962
2026-10-03 Alias added: GHSA-rx22-g9mx-qrhv

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