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CVE-2026-63405 medium CVSS 5.9

Vulnerability in github.com/anycable/anycable (CVE-2026-63405)

Summary

Vulnerability in github.com/anycable/anycable (CVE-2026-63405). Data can be tampered with by attackers. Exploitable via body_md5. Mitigation: upgrade to 1.6.15 or later.

Original description

The description as published by the source.

Summary

The Pusher-compatible REST API includes body_md5 in the HMAC signature string but never computes or verifies the MD5 of the received HTTP body, allowing anyone who observes a signed request to replay it with an entirely different body.

Details

In pusher/http.go, the Handler function extracts body_md5 from the URL query string (line 169) and includes it verbatim in stringToSign (line 175). It then verifies HMAC(stringToSign, secret) == auth_signature. After verification succeeds, handleEvents reads and parses r.Body (lines 201-212) without ever computing md5(body) and comparing it against the body_md5 that was signed. The Pusher protocol specification explicitly requires the server to verify this digest to prevent body-substitution attacks. There is also no auth_timestamp staleness check, so replays are valid indefinitely.

PoC

  1. Capture a legitimate signed POST to /apps//events?auth_key=K&auth_timestamp=T&auth_version=1.0&body_md5=LEGIT_MD5&auth_signature=SIG carrying body {"name":"safe-event","channel":"ch","data":"..."} (e.g., from TLS-terminating load-balancer logs).
  2. Send a new request with the same query string parameters but a different body:
    {"name":"injected-event","channel":"admin","data":"malicious-payload"}
  3. The server accepts the request (HMAC over stringToSign matches the original) and broadcasts the injected event to all subscribers of admin.

Impact

An attacker who can read any single signed Pushe…

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-2026-63405 has been found in github.com/anycable/anycable.
Attackers can target a specific entry point like body_md5 over the network to misuse the product.
Data can be tampered with by attackers. CVSS score: 5.9/10.
What to do: upgrade github.com/anycable/anycable to 1.6.15 or later.
If unsure, ask your IT team or search "github.com/anycable/anycable CVE-2026-63405" on the vendor's site.

CVE-2026-63405 (github.com/anycable/anycable) — CWE-345 / CVSS v3 5.9
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: body_md5 / Handler / stringToSign / handleEvents
Patched: 1.6.15 — 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-345) exists in github.com/anycable/anycable. Attackers reach the vulnerable code path via body_md5 without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of github.com/anycable/anycable. Attack surface: body_md5 / Handler / stringToSign / handleEvents.

🔥 Severity

Severity: Medium (CVSS 5.9/10). Data can be tampered with by attackers.

🔧 How to fix

Update to 1.6.15.

🛡️ 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/anycable/anycable' . 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/anycable/anycable' . | 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/anycable/anycable 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/anycable/anycable to 1.6.15

    ステージング環境で 1.6.15 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/anycable/anycable
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.6.15"}]}]

References

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