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CVE-2026-48710 CISA KEV medium CVSS 6.5

[KEV] Vulnerability in Kludex Starlette (CVE-2026-48710)

Summary

Vulnerability in Kludex Starlette (CVE-2026-48710). Risk of unauthorized operations or information disclosure. Exploitable via GET /foo. Listed in CISA KEV — actively exploited. Mitigation: upgrade to 1.0.1 or later.

Original description

The description as published by the source.

Summary

In affected versions, the HTTP Host request header was not validated before being used to reconstruct request.url. Because the routing algorithm relies on the raw HTTP path while request.url is rebuilt from the Host header, a malformed header could make request.url.path differ from the path that was actually requested. Middleware and endpoints that apply security restrictions based on request.url (rather than the raw scope path) could therefore be bypassed.

Details

When a client requests http://example.com/foo, it sends:

GET /foo HTTP/1.1
Host: example.com

Affected versions reconstructed the URL by concatenating http://{host}{path} and re-parsing the result. The Host value is only valid as a uri-host [ ":" port ] per RFC 9112 §3.2, where uri-host follows the restricted host grammar of RFC 3986 §3.2.2. When it contains characters outside that grammar - notably /, ?, or # - those characters move the path/query/fragment boundaries during re-parsing, so the parsed request.url.path no longer matches the path the server actually received. For example:

GET /foo HTTP/1.1
Host: example.com/abc?bar=

reconstructs to http://example.com/abc?bar=/foo, whose parsed path is /abc - even though routing used the real path /foo. The router still dispatches to /foo and the endpoint execute…

Source: NIST National Vulnerability Database NVD GitHub Advisory CISA KEV

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-2026-48710 has been found in Kludex Starlette.
Attackers can target a specific entry point like GET /foo over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 6.5/10.
Note: CISA has officially confirmed this is actively exploited in the wild. Treat it with elevated urgency.
What to do: upgrade Kludex Starlette to 1.0.1 or later.
If unsure, ask your IT team or search "Kludex Starlette CVE-2026-48710" on the vendor's site.

CVE-2026-48710 (Kludex Starlette) — CWE-444 / CVSS v3 6.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: GET /foo / Host header / Host / request.url
Patched: 1.0.1 — apply immediately
Listed in CISA KEV — actively exploited, treat as top priority.
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-444) exists in Kludex Starlette. Attackers reach the vulnerable code path via GET /foo without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of Kludex Starlette. Attack surface: GET /foo / Host header / Host / request.url.

🔥 Severity

Severity: Medium (CVSS 6.5/10). Risk of unauthorized operations or information disclosure. Listed in CISA KEV — actively exploited in the wild, treat as top priority.

🔧 How to fix

Update to 1.0.1.

🛡️ 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 GET /foo requests with malformed payloads or SQL meta-characters. Run grep -r 'starlette' . 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 'starlette' . | 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 starlette 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
    Hunt for indicators of compromise detect 
    grep 'GET /foo' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'

    アクセスログで GET /foo への異常なリクエスト (不正な認証ヘッダ・SQLメタ文字)を過去 30〜90日分捜索。WAF/SIEM があれば該当パスのアラート発火履歴を確認。

  3. 3
    Consider incident declaration escalate 
    Notify SOC / on-call

    CISA KEV登録済 = 実環境で悪用が観測されている。Step 2 で兆候があればインシデント対応宣言、無くてもパッチ適用までWAF強化を最優先で。

  4. 4
    Apply patch patch 
    Upgrade Kludex Starlette to 1.0.1

    ステージング環境で 1.0.1 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と、Step 2 で見つけた異常検知の続報チェックを含めること。

  5. 5
    Post-deployment verification verify 
    Replay attack against GET /foo on staging to confirm patch closes the vector

    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 2 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

PyPI starlette
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.0.1"}]}]
pip starlette
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.0.1"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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