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CVE-2026-33557 critical CVSS 9.1

Vulnerability in kafka (CVE-2026-33557)

Summary

vulnerability in kafka (CVE-2026-33557). Confidential information can be exposed externally. Exploitable via ``sasl.oauthbearer.jwt.validator.class``. Mitigation: upgrade to `4.1.2` or later.

AI summary snake-internal / snake-material-v2

A vulnerability tracked as **CVE-2026-33557** has been found in kafka. Attackers can target a specific entry point like ``sasl.oauthbearer.jwt.validator.class`` over the network to misuse the product. Confidential information can be exposed externally. CVSS score: 9.1/10. What to do: upgrade kafka to **4.1.2** or later. If unsure, ask your IT team or search "kafka CVE-2026-33557" on the vendor's site.
CVE-2026-33557 (kafka) — CWE-1285 / CVSS v3 9.1 Attack vector: remote (network-reachable) / unauthenticated / no user interaction Attack surface: `sasl.oauthbearer.jwt.validator.class` / `preferred_username` Patched: `4.1.2` — 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-1285) exists in kafka. Attackers reach the vulnerable code path via ``sasl.oauthbearer.jwt.validator.class`` without authentication.
📍 Affected scope
kafka — . Attack surface: `sasl.oauthbearer.jwt.validator.class` / `preferred_username`.
🔥 Severity
Severity: Critical (CVSS 9.1/10). Confidential information can be exposed externally
🔧 How to fix
Update to **4.1.2**.
🛡️ 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 'kafka' .` against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response Actions (7 steps)

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

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

  2. 6
    Apply patch patch 
    Upgrade kafka to 4.1.2

    ステージング環境で 4.1.2 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と、Step 3 で見つけた異常検知の続報チェックを含めること。

  3. 7
    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 Step 3 と同じログクエリでアラート再発が無いか継続監視。

Affected packages

Bitnami kafka
[{"type":"SEMVER","events":[{"introduced":"4.1.0"},{"fixed":"4.1.2"}]}]

References

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