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CVE-2026-48487 medium CVSS 5.3

Vulnerability in zeroconf (CVE-2026-48487)

Summary

Vulnerability in zeroconf (CVE-2026-48487). Data can be tampered with by attackers. Exploitable via _read_character_string. Mitigation: upgrade to 0.149.16 or later.

Original description

The description as published by the source.

Impact

_read_character_string and _read_string in src/zeroconf/_protocol/incoming.py sliced self.data[self.offset : self.offset + length] and advanced self.offset by the declared length without checking it against self._data_len. Python's slice silently returns fewer bytes when the end index runs past the buffer, so a record whose 16-bit RDLENGTH (RFC 1035 §3.2.1) over-advertised by tens of kilobytes was constructed from a truncated payload, appended to DNSIncoming._answers, and committed to the cache before any later parse failure surfaced. The follow-up _read_name for the next record then failed, but the corrupt record had already entered the answer list and propagated to DNSCache and ServiceInfo.

Any unauthenticated host on the local link (UDP/5353, 224.0.0.251 / ff02::fb) can multicast a single mDNS response carrying a TXT, HINFO, or A/AAAA record that advertises rdlength=65535 and only a handful of real payload bytes; consumers calling ServiceInfo.properties then parse the truncated bytes as if they matched the wire, and downstream integrations (Home Assistant and other zeroconf-driven discovery) trust the decoded record. The bug is parser-state desync rather than RCE, but it seeds the cache with attacker-shaped key/value and address records for a TTL window and is a building block for higher-impact chains.

The impact is likely lower than the other recently released advisories as there is no additional risk of OOM so the severity was ma…

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-2026-48487 has been found in zeroconf.
Attackers can target a specific entry point like _read_character_string over the network to misuse the product.
Data can be tampered with by attackers. CVSS score: 5.3/10.
What to do: upgrade zeroconf to 0.149.16 or later.
If unsure, ask your IT team or search "zeroconf CVE-2026-48487" on the vendor's site.

CVE-2026-48487 (zeroconf) — CWE-130 / CVSS v3 5.3
Attack vector: adjacent-network / unauthenticated / no user interaction
Attack surface: _read_character_string / _read_string / self.offset / length
Patched: 0.149.16 — 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-130) exists in zeroconf. Attackers reach the vulnerable code path via _read_character_string without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of zeroconf. Attack surface: _read_character_string / _read_string / self.offset / length.

🔥 Severity

Severity: Medium (CVSS 5.3/10). Data can be tampered with by attackers.

🔧 How to fix

Update to 0.149.16.

🛡️ 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 0.149.16

    ステージング環境で 0.149.16 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":"0.149.16"}]}]
PyPI zeroconf
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.149.16"}]}]

References

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