Ruby rack: From 3.0 until 3.1.23 and 3.2.8, Rack::Request#host_with_port, #base_url, and #url can return an
Affects ruby-rackSource GCVE Database
Not known to be exploited · CVSS 4.8 Medium · fixed in 3.1.23 : update ruby-rack when convenient.
Data as of 13 Nov 2026, 22:38 UTC
Thin evidence
One scorer or none| CNA (GitHub_M) | CVSS 3.1 | 4.8 |
|---|
- Patch
- Available – fixed in 3.1.23
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:NExploitation evidence
Disclosed: evidence found.
CVE published 9 Nov 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 13 Nov 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.10ruby-rackpkg:deb/ubuntu/ruby-rack?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSruby-rackpkg:deb/ubuntu/ruby-rack?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSruby-rackpkg:deb/ubuntu/ruby-rack?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu Pro 22.04 LTSruby-rackpkg:deb/ubuntu/ruby-rack?arch=source&distro=esm-apps/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.
AI-suggested
Upgrade Ruby Rack to version 3.1.23 or later, or 3.2.8 or later, where this vulnerability is fixed. Applications should also implement independent host allowlisting or validation rather than relying solely on these methods for host information. Since the vendor advisory confirms fixes in these versions, applying these updates fully mitigates the issue.
Description
A vulnerability in Ruby Rack versions from 3.0 up to but not including 3.1.23 and 3.2.8 allows certain methods to return attacker-controlled invalid host information from HTTP headers. This can lead to redirect manipulation, allowlist bypass, or unescaped markup reflection in applications that rely on these methods for absolute URLs or origin checks. Rails applications are not affected due to method overrides. The issue is fixed in Rack versions 3.1.23 and 3.2.8.
References
- ubuntu.com/security/CVE-2026-125109 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-125109 (opens in a new tab)
- github.com/rack/rack/security/advisories/GHSA-2j8w-xcrc-x985 (opens in a new tab)
- github.com/rack/rack/commit/4380381a56dc52556a436d6d794c8e18dc8b0565 (opens in a new tab)
- github.com/rack/rack/commit/49386f460286b7346c7003b69a839de782cc8a39 (opens in a new tab)
- github.com/rack/rack/releases/tag/v3.1.23 (opens in a new tab)
- github.com/rack/rack/releases/tag/v3.2.8 (opens in a new tab)