Vulnerability in ruby-bundler (ALPINE-CVE-2021-43809)
Summary
Vulnerability in ruby-bundler (ALPINE-CVE-2021-43809). Successful exploitation can lead to full system takeover. Exploitable via Bundler. Mitigation: upgrade to 2.2.33-r0 or later.
Original description
The description as published by the source.
Bundler is a package for managing application dependencies in Ruby. In bundler versions before 2.2.33, when working with untrusted and apparently harmless Gemfile's, it is not expected that they lead to execution of external code, unless that's explicit in the ruby code inside the Gemfile itself. However, if the Gemfile includes gem entries that use the git option with invalid, but seemingly harmless, values with a leading dash, this can be false. To handle dependencies that come from a Git repository instead of a registry, Bundler uses various commands, such as git clone. These commands are being constructed using user input (e.g. the repository URL). When building the commands, Bundler versions before 2.2.33 correctly avoid Command Injection vulnerabilities by passing an array of arguments instead of a command string. However, there is the possibility that a user input starts with a dash (-) and is therefore treated as an optional argument instead of a positional one. This can lead to Code Execution because some of the commands have options that can be leveraged to run arbitrary executables. Since this value comes from the Gemfile file, it can contain any character, including a leading dash.
To exploit this vulnerability, an attacker has to craft a directory containing a Gemfile file that declares a dependency that is located in a Git repository. This dependency has to have a Git URL in the form of -u./payload. This URL will be used to construct a G…
Source: OSV.dev (Open Source Vulnerabilities) OSV
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as ALPINE-CVE-2021-43809 has been found in ruby-bundler.
Attackers can target a specific entry point like Bundler over the network to misuse the product.
Successful exploitation can lead to full system takeover.
What to do: upgrade ruby-bundler to 2.2.33-r0 or later.
If unsure, ask your IT team or search "ruby-bundler ALPINE-CVE-2021-43809" on the vendor's site.
ALPINE-CVE-2021-43809 (ruby-bundler)
Attack vector: local
Attack surface: Bundler / bundler / Gemfile / gem
Patched: 2.2.33-r0 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (unclassified) exists in ruby-bundler. Attackers reach the vulnerable code path via Bundler.
Check the vendor advisory for the affected versions of ruby-bundler. Attack surface: Bundler / bundler / Gemfile / gem.
Severity: ?. Successful exploitation can lead to full system takeover.
Update to 2.2.33-r0.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'ruby-bundler' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'ruby-bundler' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
ruby-bundlerを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade ruby-bundler to 2.2.33-r0ステージング環境で 2.2.33-r0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory security.alpinelinux.org