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CVE-2026-48045 medium CVSS 6.5

Vulnerability in zeroconf (CVE-2026-48045)

Summary

Vulnerability in zeroconf (CVE-2026-48045). Risk of unauthorized operations or information disclosure. Exploitable via AsyncListener.handle_query_or_defer. Mitigation: upgrade to 0.149.12 or later.

Original description

The description as published by the source.

Impact

AsyncListener.handle_query_or_defer retained every truncated (TC-bit) incoming query in self._deferred[addr] and armed a per-addr timer in self._timers[addr] that flushed the reassembled query within ~500 ms (RFC 6762 §18.5). Neither the per-addr list nor the number of distinct addr keys was capped, and the dedup check (for incoming in reversed(deferred): if incoming.data == msg.data) ran O(N) over the per-addr list on every arrival.

Any unauthenticated host on the local link (UDP/5353, 224.0.0.251 / ff02::fb) can stream byte-distinct TC-flagged mDNS queries — each up to _MAX_MSG_ABSOLUTE = 8966 bytes, with DNSIncoming retaining the raw data buffer plus parsed-record state. Trivially spoofed source IPs multiply the effect across _deferred / _timers, and the O(N) data compare burns CPU quadratically as each per-addr queue grows. On memory-constrained deployments (Home Assistant on Raspberry-Pi-class hardware is the canonical victim) sustained traffic OOM-kills the process; under lighter load, the per-arrival scan and event-loop scheduler starvation break unrelated zeroconf consumers (discovery, registration, ServiceBrowser callbacks).

Patches

Fixed in zeroconf 0.149.12 (PR #1751). Upgrade to >= 0.149.12.

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, gu…

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-2026-48045 has been found in zeroconf.
Attackers can target a specific entry point like AsyncListener.handle_query_or_defer 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 0.149.12 or later.
If unsure, ask your IT team or search "zeroconf CVE-2026-48045" on the vendor's site.

CVE-2026-48045 (zeroconf) — CWE-400 / CVSS v3 6.5
Attack vector: adjacent-network / unauthenticated / no user interaction
Attack surface: AsyncListener.handle_query_or_defer / addr / DNSIncoming / data
Patched: 0.149.12 — 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-400) exists in zeroconf. Attackers reach the vulnerable code path via AsyncListener.handle_query_or_defer without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of zeroconf. Attack surface: AsyncListener.handle_query_or_defer / addr / DNSIncoming / data.

🔥 Severity

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

🔧 How to fix

Update to 0.149.12.

🛡️ 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 0.149.12

    ステージング環境で 0.149.12 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":"0.149.12"}]}]
PyPI zeroconf
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.149.12"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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