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CVE-2026-47180 medium CVSS 6.5

Vulnerability in zeroconf (CVE-2026-47180)

Summary

Vulnerability in zeroconf (CVE-2026-47180). Risk of unauthorized operations or information disclosure. Exploitable via DNSIncoming._decode_labels_at_offset. Mitigation: upgrade to 0.149.5 or later.

Original description

The description as published by the source.

Impact

DNSIncoming._decode_labels_at_offset recurses once per DNS-name compression pointer (RFC 1035 §4.1.4). Pointer cycles and label counts were capped, but the chain length of unique forward pointers was not. A single ~3 kB mDNS packet carrying ~1500 chained pointers drives the recursion past CPython's default limit, and RecursionError was not listed in DECODE_EXCEPTIONS, so it escaped DNSIncoming.__init__ and was logged by asyncio's default exception handler.

Any unauthenticated host on the local link (UDP/5353, 224.0.0.251 / ff02::fb) can degrade the mDNS listener; that includes a guest on the same Wi-Fi, a compromised IoT device, or a container on a shared bridge. Replaying at a few hertz produces sustained CPU burn and log flooding, and mDNS-dependent features (HomeKit, Chromecast/Matter, AirPlay, printers) degrade while the attack is in flight.

Patches

Fixed in zeroconf 0.149.5 (PR #1719).
Upgrade to >= 0.149.5.

Workarounds

There is no in-process workaround; upgrading is the fix. Otherwise, restrict mDNS (UDP/5353) to trusted Layer-2 segments via AP client isolation, guest-network separation, or host firewall rules.

Resources

Source: GitHub Security Advisories (Global) 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-2026-47180 has been found in zeroconf.
Attackers can target a specific entry point like DNSIncoming._decode_labels_at_offset over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 6.5/10.
What to do: upgrade zeroconf to 0.149.5 or later.
If unsure, ask your IT team or search "zeroconf CVE-2026-47180" on the vendor's site.

CVE-2026-47180 (zeroconf) — CWE-674 / CVSS v3 6.5
Attack vector: adjacent-network / unauthenticated / no user interaction
Attack surface: DNSIncoming._decode_labels_at_offset / RecursionError / DECODE_EXCEPTIONS / DNSIncoming.__init__
Patched: 0.149.5 — apply immediately
Workaround: There is no in-process workaround; upgrading is the fix.
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-674) exists in zeroconf. Attackers reach the vulnerable code path via DNSIncoming._decode_labels_at_offset without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of zeroconf. Attack surface: DNSIncoming._decode_labels_at_offset / RecursionError / DECODE_EXCEPTIONS / DNSIncoming.__init__.

🔥 Severity

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

🔧 How to fix

Update to 0.149.5.

🛡️ Workaround

Workaround: There is no in-process workaround; upgrading is the fix.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'zeroconf' . 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 'zeroconf' . | 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 zeroconf 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 temporary workaround mitigate 
    There is no in-process workaround; upgrading is the fix.

    パッチが適用されるまでの応急処置として、There is no in-process workaround; upgrading is the fix. を実施。回避策の副作用 (機能低下) を確認した上で。

  3. 3
    Apply patch patch 
    Upgrade zeroconf to 0.149.5

    ステージング環境で 0.149.5 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。

  4. 4
    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

pip zeroconf
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.149.5"}]}]
PyPI zeroconf
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.149.5"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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