CVE-2026-26962: Ruby rack · From version 3.2.0 to before version 3.2.6, Rack::Multipart::Parser unfolds folded
Affects ruby-rackSource GCVE Database
Not known to be exploited · CVSS 6.5 Medium · fixed in 2.2.7-1ubuntu0.7 : update ruby-rack when convenient.
Data as of 3 Nov 2026, 23:14 UTC
- Patch
- Available – fixed in 2.2.7-1ubuntu0.7, 3.1.16-0.1ubuntu0.3
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:NExploitation evidence
Disclosed: evidence found.
CVE published 2 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 3 Nov 2026.
What to do
Upgrade the Ubuntu ruby-rack to 2.2.7-1ubuntu0.7 (package) or 3.1.16-0.1ubuntu0.3 (package).
Patches and advisories
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSruby-rackpkg:deb/ubuntu/ruby-rack?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 25.10ruby-rackpkg:deb/ubuntu/ruby-rack?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSruby-rackpkg:deb/ubuntu/ruby-rack?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 22.04 LTSruby-rackpkg:deb/ubuntu/ruby-rack?arch=source&distro=jammyOther threats | Affected
| Fixed in– |
Ubuntu Pro 20.04 LTSruby-rackpkg:deb/ubuntu/ruby-rack?arch=source&distro=esm-apps/focalOther threats | Affected
| Fixed in– |
Ubuntu Pro 18.04 LTSruby-rackpkg:deb/ubuntu/ruby-rack?arch=source&distro=esm-apps/bionicOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
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.