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CVE-2021-23351

Vulnerability in github.com/pires/go-proxyproto (CVE-2021-23351)

Summary

Vulnerability in github.com/pires/go-proxyproto (CVE-2021-23351). Risk of unauthorized operations or information disclosure. Exploitable via bufio.Reader. Mitigation: upgrade to 0.5.0 or later.

Original description

The description as published by the source.

The package github.com/pires/go-proxyproto before 0.5.0 are vulnerable to Denial of Service (DoS) via the parseVersion1() function. The reader in this package is a default bufio.Reader wrapping a net.Conn. It will read from the connection until it finds a newline. Since no limits are implemented in the code, a deliberately malformed V1 header could be used to exhaust memory in a server process using this code - and create a DoS. This can be exploited by sending a stream starting with PROXY and continuing to send data (which does not contain a newline) until the target stops acknowledging. The risk here is small, because only trusted sources should be allowed to send proxy protocol headers.

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-2021-23351 has been found in github.com/pires/go-proxyproto.
Attackers can target a specific entry point like bufio.Reader over the network to misuse the product.
Risk of unauthorized operations or information disclosure.
What to do: upgrade github.com/pires/go-proxyproto to 0.5.0 or later.
If unsure, ask your IT team or search "github.com/pires/go-proxyproto CVE-2021-23351" on the vendor's site.

CVE-2021-23351 (github.com/pires/go-proxyproto) — CWE-400
Attack vector: remote (network-reachable) / no user interaction
Attack surface: bufio.Reader / net.Conn
Patched: 0.5.0 — 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 (CWE-400) exists in github.com/pires/go-proxyproto. Attackers reach the vulnerable code path via bufio.Reader.

📍 Affected scope

Check the vendor advisory for the affected versions of github.com/pires/go-proxyproto. Attack surface: bufio.Reader / net.Conn.

🔥 Severity

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

🔧 How to fix

Update to 0.5.0.

🛡️ 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 'github.com/pires/go-proxyproto' . 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. 1
    Identify exposure identify 
    grep -r 'github.com/pires/go-proxyproto' . | 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 github.com/pires/go-proxyproto を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply patch patch 
    Upgrade github.com/pires/go-proxyproto to 0.5.0

    ステージング環境で 0.5.0 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. 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。

Affected packages

Go github.com/pires/go-proxyproto
[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"0.5.0"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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