Description
Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Static#applicable_rules evaluates several header_rules types against the raw URL-encoded PATH_INFO, while the underlying file-serving path is decoded before the file is served. As a result, a request for a URL-encoded variant of a static path can serve the same file without the headers that header_rules were intended to apply. In deployments that rely on Rack::Static to attach security-relevant response headers to static content, this can allow an attacker to bypass those headers by requesting an encoded form of the path. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| rack | rack | < 2.2.23, >= 3.0.0.beta1, < 3.1.21, >= 3.2.0, < 3.2.6 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | ruby-rack | 3.2.6-2 | — |
| Debian 13 | ruby-rack | 3.1.20-0+deb13u2 | — |
| Debian 12 | ruby-rack | 2.2.22-0+deb12u2 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.04 LTS | ruby-rack | 3.2.4-1ubuntu1.1 | USN-8989-1 |
| Ubuntu 25.10 | ruby-rack | 3.1.16-0.1ubuntu0.3 | — |
| Ubuntu 24.04 LTS | ruby-rack | 2.2.7-1ubuntu0.7 | — |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 22.04 LTS | ruby-rack | 2.1.4-5ubuntu1.2+esm3 | — |
| Ubuntu Pro 18.04 LTS | ruby-rack | 1.6.4-4ubuntu0.2+esm10 | — |
| Ubuntu Pro 16.04 LTS | ruby-rack | No fix yet | — |
| Ubuntu Pro 14.04 LTS | ruby-rack | No fix yet | — |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP6 | rmt-server | 2.27-150500.3.47.1 | SUSE-SU-2026:2487-1 |
| SLES 15 SP5 | rmt-server | 2.27-150500.3.47.1 | SUSE-SU-2026:2487-1 |
Show 5 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 16.0 | rmt-server | 3.1.0-160000.1.1 | SUSE-SU-2026:23321-1 |
| SLES for SAP 15 SP6 | rmt-server | 2.27-150500.3.47.1 | SUSE-SU-2026:2487-1 |
| SLES for SAP 15 SP5 | rmt-server | 2.27-150500.3.47.1 | SUSE-SU-2026:2487-1 |
| SLES 16.0 | rmt-server | 3.1.0-160000.1.1 | SUSE-SU-2026:23321-1 |
| SLE HPC 15 SP5 | rmt-server | 2.27-150500.3.47.1 | SUSE-SU-2026:2487-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | rubygem-rack-2.2 | 2.2.23-1.1 | openSUSE-SU-2026:10508-1 |
| openSUSE Leap 16.0 | rmt-server | 3.1.0-160000.1.1 | openSUSE-SU-2026:21640-1 |
Wolfi
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Wolfi rolling | kube-fluentd-operator | 1.18.2-r60 | — |
| Wolfi rolling | logstash-9.3 +2 | 9.3.3-r2 | — |
| Wolfi rolling | ruby3.2-rack-2.2 +2 | 2.2.23-r0 | — |
| Wolfi rolling | ruby3.3-rack-2.2 | 2.2.22-r0 | — |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| RubyGems | rack | < 2.2.23 | 2.2.23 | GHSA-q4qf-9j86-f5mh |
| RubyGems | rack | >= 3.0.0.beta1, < 3.1.21 | 3.1.21 | GHSA-q4qf-9j86-f5mh |
| RubyGems | rack | >= 3.2.0, < 3.2.6 | 3.2.6 | GHSA-q4qf-9j86-f5mh |
Advisories 6
- USN-8989-1 ruby-rack vulnerabilities Ubuntu Security Notices (USN) · Nov 4, 2026
- SUSE-SU-2026:23321-1 Security update for rmt-server SUSE / openSUSE Security Updates · Sep 10, 2026
- WID-SEC-2026-1687 IBM License Metric Tool: Mehrere Schwachstellen ermöglichen nicht spezifizierten Angriff BSI CERT-Bund (WID) · Sep 1, 2026
- openSUSE-SU-2026:21640-1 Security update for rmt-server SUSE / openSUSE Security Updates · Aug 27, 2026
- SUSE-SU-2026:2487-1 Security update for rmt-server SUSE / openSUSE Security Updates · Jun 24, 2026
- openSUSE-SU-2026:10508-1 ruby4.0-rubygem-rack-2.2-2.2.23-1.1 on GA media SUSE / openSUSE Security Updates · Apr 9, 2026