Description
Active Support is a toolkit of support libraries and Ruby core extensions extracted from the Rails framework. Prior to versions 8.1.2.1, 8.0.4.1, and 7.2.3.1, `SafeBuffer#%` does not propagate the `@html_unsafe` flag to the newly created buffer. If a `SafeBuffer` is mutated in place (e.g. via `gsub!`) and then formatted with `%` using untrusted arguments, the result incorrectly reports `html_safe? == true`, bypassing ERB auto-escaping and possibly leading to XSS. Versions 8.1.2.1, 8.0.4.1, and 7.2.3.1 contain a patch.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| rails | activesupport | >= 8.1.0.beta1, < 8.1.2.1, >= 8.0.0.beta1, < 8.0.4.1, < 7.2.3.1 | — |
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 | rails | 2:7.2.3.1+dfsg-1 | — |
| Debian 13 | rails | 2:7.2.2.2+dfsg-2~deb13u2 | — |
| Debian 12 | rails | 2:6.1.7.10+dfsg-1~deb12u3 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | rails | No fix yet | — |
| Ubuntu 26.04 LTS | rails | No fix yet | — |
| Ubuntu 25.10 | rails | No fix yet | — |
| Ubuntu 24.04 LTS | rails | No fix yet | — |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 22.04 LTS | rails | No fix yet | — |
| Ubuntu Pro 20.04 LTS | rails | No fix yet | — |
| Ubuntu Pro 18.04 LTS | rails | No fix yet | — |
| Ubuntu Pro 16.04 LTS | rails | No fix yet | — |
Wolfi
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Wolfi rolling | cinc-auditor | 7.0.107-r1 | — |
| Wolfi rolling | kube-fluentd-operator | 1.18.2-r60 | — |
| Wolfi rolling | kube-logging-operator-fluentd-outputs | 6.4.0-r9 | — |
| Wolfi rolling | ruby3.2-rails-8.1 | 8.1.3-r0 | — |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| RubyGems | activesupport | >= 8.1.0.beta1, < 8.1.2.1 | 8.1.2.1 | GHSA-89vf-4333-qx8v |
| RubyGems | activesupport | >= 8.0.0.beta1, < 8.0.4.1 | 8.0.4.1 | GHSA-89vf-4333-qx8v |
| RubyGems | activesupport | < 7.2.3.1 | 7.2.3.1 | GHSA-89vf-4333-qx8v |
Advisories 2
- WID-SEC-2026-0833 Ruby on Rails: Mehrere Schwachstellen BSI CERT-Bund (WID) · Oct 8, 2026
- WID-SEC-2026-1687 IBM License Metric Tool: Mehrere Schwachstellen ermöglichen nicht spezifizierten Angriff BSI CERT-Bund (WID) · Sep 1, 2026
References
- https://github.com/rails/rails/security/advisories/GHSA-89vf-4333-qx8v
- https://github.com/rails/rails/commit/50d732af3b7c8aaf63cbcca0becbc00279b215b7
- https://github.com/rails/rails/commit/6e8a81108001d58043de9e54a06fca58962fc2db
- https://github.com/rails/rails/commit/c1ad0e8e1972032f3395853a5e99cea035035beb
- https://github.com/rails/rails/releases/tag/v7.2.3.1
- https://github.com/rails/rails/releases/tag/v8.0.4.1
- https://github.com/rails/rails/releases/tag/v8.1.2.1