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VulnerabilityPublished Updated

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

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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

CVSS 3.1 base score
6.5Medium
How severe the flaw is on the 0–10 CVSS scale.
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:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 2 Apr 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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).

Affected software

ProductAffectedFixed in
Ubuntu 26.04 LTSruby-rackpkg:deb/ubuntu/ruby-rack?arch=source&distro=resoluteOther threatsAffected
  • 3.1.16-0.1 – 3.2.4-1ubuntu1.1
5 affected builds
Fixed in–
Ubuntu 25.10ruby-rackpkg:deb/ubuntu/ruby-rack?arch=source&distro=questingOther threatsAffected
  • <3.1.16-0.1ubuntu0.3
Fixed in
  • 3.1.16-0.1ubuntu0.3
Ubuntu 24.04 LTSruby-rackpkg:deb/ubuntu/ruby-rack?arch=source&distro=nobleOther threatsAffected
  • <2.2.7-1ubuntu0.7
Fixed in
  • 2.2.7-1ubuntu0.7
Ubuntu 22.04 LTSruby-rackpkg:deb/ubuntu/ruby-rack?arch=source&distro=jammyOther threatsAffected
  • 2.1.4-3 – 2.1.4-5ubuntu1.2
6 affected builds
Fixed in–
Ubuntu Pro 20.04 LTSruby-rackpkg:deb/ubuntu/ruby-rack?arch=source&distro=esm-apps/focalOther threatsAffected
  • 2.0.6-3 – 2.0.7-2ubuntu0.1+esm10
13 affected builds
Fixed in–
Ubuntu Pro 18.04 LTSruby-rackpkg:deb/ubuntu/ruby-rack?arch=source&distro=esm-apps/bionicOther threatsAffected
  • 1.6.4-4 – 1.6.4-4ubuntu0.2+esm10
12 affected builds
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.

References

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