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CVE-2026-33805
high
CVSS 8.6
Vulnerability in @fastify/reply-from (CVE-2026-33805)
Summary
vulnerability in @fastify/reply-from (CVE-2026-33805). Data can be tampered with by attackers. Exploitable via ``Connection``. Mitigation: upgrade to `12.6.2` or later.
AI summary snake-internal / snake-material-v2
A vulnerability tracked as **CVE-2026-33805** has been found in @fastify/reply-from.
Attackers can target a specific entry point like ``Connection`` over the network to misuse the product.
Data can be tampered with by attackers. CVSS score: 8.6/10.
What to do: upgrade @fastify/reply-from to **12.6.2** or later.
If unsure, ask your IT team or search "@fastify/reply-from CVE-2026-33805" on the vendor's site.
CVE-2026-33805 (@fastify/reply-from) — CWE-644 / CVSS v3 8.6
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: `Connection` / `rewriteRequestHeaders` / `connection` / `index.js`
Patched: `12.6.2` — 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-644) exists in @fastify/reply-from. Attackers reach the vulnerable code path via ``Connection`` without authentication.
📍 Affected scope
@fastify/reply-from — . Attack surface: `Connection` / `rewriteRequestHeaders` / `connection` / `index.js`.
🔥 Severity
Severity: High (CVSS 8.6/10). Data can be tampered with by attackers
🔧 How to fix
Update to **12.6.2**.
🛡️ 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 '@fastify/reply-from' .` 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
-
1Identify exposure identify
grep -r '@fastify/reply-from' . | 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 `@fastify/reply-from` を grep し、稼働しているサービス・バージョンを把握する。
-
6Apply patch patch
Upgrade @fastify/reply-from to 12.6.2ステージング環境で 12.6.2 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。
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7Post-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
npm
@fastify/reply-from
[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"12.6.2"}]}]
npm
@fastify/http-proxy
[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"11.4.4"}]}]
References
- advisory https://nvd.nist.gov/vuln/detail/CVE-2026-33805
- exploit 134c704f-9b21-4f2e-91b3-4a467353bcc0
- package https://github.com/fastify/fastify-reply-from
- patch ce714d77-add3-4f53-aff5-83d477b104bb
- web https://github.com/advisories/GHSA-gwhp-pf74-vj37
- web 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- web 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- web 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- web 0b0ca135-0b70-47e7-9f44-1890c2a1c46c