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CVE-2026-85078 medium CVSS 6.5

Vulnerability in sanic (CVE-2026-85078)

Summary

Vulnerability in sanic (CVE-2026-85078). Risk of unauthorized operations or information disclosure. Exploitable via GET /this-path-should-not-exist. Mitigation: upgrade to 25.12.1 or later.

Original description

The description as published by the source.

Description

Sanic's HTTP/1.1 chunked-body handling does not fully consume the trailer-part after the terminating 0\r\n chunk. Because of that, attacker-controlled bytes left in the connection buffer after the first chunked request can be interpreted as the start of a new HTTP request on the same keep-alive connection. In the attached verified proof, a single outer POST / request that correctly returns 405 Method Not Allowed is followed, within the same TCP send, by a hidden second request smuggled through the chunked trailer area. Sanic parses and executes that second request as a real independent request.

The issue is a request-boundary integrity failure in Sanic's core HTTP/1.1 parser. The verified impact is not speculative. The attached proof shows that one TCP payload produces two server responses: first the expected 405 for the outer POST /, then a separate 200 OK for a hidden GET /. A second exploit variant changes the hidden request path and receives a real 404 Not Found, proving that the hidden second request is not a hard-coded artifact but an actually routed backend request. A control case with a two-character trailer field name shifts the leftover bytes from GET to :GET, which changes the second response accordingly and confirms that the root cause is incorrect trailer consumption rather than legitimate pipelining.

Steps To Reproduce

  1. Start a Sanic HTTP/1.1 service on a keep-alive connection path. In the verified run, the local tar…

Source: NIST National Vulnerability Database NVD GitHub Advisory

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-2026-85078 has been found in sanic.
Attackers can target a specific entry point like GET /this-path-should-not-exist over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 6.5/10.
What to do: upgrade sanic to 25.12.1 or later.
If unsure, ask your IT team or search "sanic CVE-2026-85078" on the vendor's site.

CVE-2026-85078 (sanic) — CWE-444 / CVSS v3 6.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: GET /this-path-should-not-exist / GET
Patched: 25.12.1 — 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 (CWE-444) exists in sanic. Attackers reach the vulnerable code path via GET /this-path-should-not-exist without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of sanic. Attack surface: GET /this-path-should-not-exist / GET.

🔥 Severity

Severity: Medium (CVSS 6.5/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 25.12.1.

🛡️ 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 /this-path-should-not-exist requests with malformed payloads or SQL meta-characters. Run grep -r 'sanic' . 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 'sanic' . | 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 sanic 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 /this-path-should-not-exist' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'

    アクセスログで GET /this-path-should-not-exist 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
    Apply patch patch 
    Upgrade sanic to 25.12.1

    ステージング環境で 25.12.1 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。

  4. 4
    Post-deployment verification verify 
    Replay attack against GET /this-path-should-not-exist 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

pip sanic
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"25.12.1"}]}]

References

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