Vulnerability in OAuth2 Proxy (CVE-2020-11053)

Summary

Vulnerability in OAuth2 Proxy (CVE-2020-11053). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 5.1.1 or later.

Original description

The description as published by the source.

In OAuth2 Proxy before 5.1.1, there is an open redirect vulnerability. Users can provide a redirect address for the proxy to send the authenticated user to at the end of the authentication flow. This is expected to be the original URL that the user was trying to access. This redirect URL is checked within the proxy and validated before redirecting the user to prevent malicious actors providing redirects to potentially harmful sites. However, by crafting a redirect URL with HTML encoded whitespace characters the validation could be bypassed and allow a redirect to any URL provided. This has been patched in 5.1.1.

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-2020-11053 has been found in OAuth2 Proxy.
Risk of unauthorized operations or information disclosure.
What to do: upgrade OAuth2 Proxy to 5.1.1 or later.
If unsure, ask your IT team or search "OAuth2 Proxy CVE-2020-11053" on the vendor's site.

CVE-2020-11053 (OAuth2 Proxy)
Attack vector: remote (network-reachable) / unauthenticated
Patched: 5.1.1 — 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.

❓ What is the problem

A vulnerability (unclassified) exists in OAuth2 Proxy.

📍 Affected scope

Check the vendor advisory for the affected versions of OAuth2 Proxy.

🔥 Severity

Severity: ?. Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 5.1.1.

🛡️ 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. Audit SBOM/dependencies to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

1
Identify exposure identify
```
Audit SBOM/dependencies for affected components.
```
資産台帳・SBOM・依存マニフェストで OAuth2 Proxy を使っているサービスとバージョンを洗い出す。
2
Apply patch patch
```
Upgrade OAuth2 Proxy to 5.1.1
```
ステージング環境で 5.1.1 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。
3
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 github.com