medium4.8
CVE-2026-26962
Rack's improper unfolding of folded multipart headers preserves CRLF in parsed parameter values
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| rubygems | rack | >= 3.2.0, < 3.2.6 | 3.2.6 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Rack | Rack | from 3.2.0 before 3.2.6 |