Vulnerability in Jenkins (CVE-2021-21605)

Summary

Vulnerability in Jenkins (CVE-2021-21605). Successful exploitation can lead to full system takeover. Exploitable via config.xml.

Original description

The description as published by the source.

Jenkins 2.274 and earlier, LTS 2.263.1 and earlier allows users with Agent/Configure permission to choose agent names that cause Jenkins to override the global config.xml file.

Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory 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 CVE-2021-21605 has been found in Jenkins.
Attackers can target a specific entry point like config.xml over the network to misuse the product.
Successful exploitation can lead to full system takeover.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Jenkins CVE-2021-21605" on the vendor's site.

CVE-2021-21605 (Jenkins)
Attack vector: remote (network-reachable)
Attack surface: config.xml
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.

❓ What is the problem

A vulnerability (unclassified) exists in Jenkins. Attackers reach the vulnerable code path via config.xml.

📍 Affected scope

Check the vendor advisory for the affected versions of Jenkins. Attack surface: config.xml.

🔥 Severity

Severity: ?. Successful exploitation can lead to full system takeover.

🔧 How to fix

Update to the patched release per vendor advisory.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'Jenkins' . 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

1
Identify exposure identify
```
grep -r 'Jenkins' . | 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 Jenkins を grep し、稼働しているサービス・バージョンを把握する。
2
Post-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。

References

advisory jenkins.io