BREW-HOMEASSISTANT-CLI-C… (GHSA-RFG2-PJW2-56X2)
Vulnerability from osv_homebrew – Published: 2026-08-13 16:56 – Updated: 2026-09-17 17:53 – Source websiteImpact
DNSCache._async_add inserted every response record into cache, _expirations, _expire_heap, and service_cache with no cap on entry count. The only pre-existing protection was a PTR TTL floor (_DNS_PTR_MIN_TTL = 1125 s, RFC 6762 §10), which actually prolonged attacker-injected records, and a periodic async_expire on _CACHE_CLEANUP_INTERVAL = 10 s that could not keep up with a flood.
Any unauthenticated host on the local link (UDP/5353, 224.0.0.251 / ff02::fb) can multicast valid mDNS responses with unique names (RFC 6762 §11 allows up to 253 bytes each) and watch them accumulate. On memory-constrained deployments (Home Assistant on Raspberry-Pi-class hardware is the canonical victim) sustained traffic OOM-kills the process; under lighter load, every cache lookup and every periodic expiry pass grows linearly slower, starving asyncio and breaking unrelated zeroconf consumers (discovery, registration, ServiceBrowser callbacks). A second variant — re-multicasting cached records with shifting TTLs — grows _expire_heap unbounded between cleanup runs without touching cache or _total_records.
Patches
Fixed in zeroconf 0.149.6 (PR #1718). Upgrade to >= 0.149.6.
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
- PR #1718, fix
- Issue #1715, public tracking issue
- RFC 6762 §10, RFC 6762 §11, CWE-400
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "zeroconf",
"resource_purl": "pkg:pypi/zeroconf@0.150.0",
"upstream_fixed_in": "0.149.7"
},
"package": {
"ecosystem": "Homebrew",
"name": "homeassistant-cli",
"purl": "pkg:brew/homeassistant-cli"
},
"ranges": [
{
"events": [
{
"introduced": "0.5.0"
},
{
"fixed": "1.0.0_2"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/zeroconf@0.150.0",
"name": "zeroconf",
"resource": "zeroconf",
"strategy": "registry",
"subject_version": "0.150.0"
}
]
},
"details": "### Impact\n\n`DNSCache._async_add` inserted every response record into `cache`, `_expirations`, `_expire_heap`, and `service_cache` with no cap on entry count. The only pre-existing protection was a PTR TTL floor (`_DNS_PTR_MIN_TTL = 1125` s, RFC 6762 \u00a710), which actually *prolonged* attacker-injected records, and a periodic `async_expire` on `_CACHE_CLEANUP_INTERVAL = 10` s that could not keep up with a flood.\n\nAny unauthenticated host on the local link (UDP/5353, `224.0.0.251` / `ff02::fb`) can multicast valid mDNS responses with unique names (RFC 6762 \u00a711 allows up to 253 bytes each) and watch them accumulate. On memory-constrained deployments (Home Assistant on Raspberry-Pi-class hardware is the canonical victim) sustained traffic OOM-kills the process; under lighter load, every cache lookup and every periodic expiry pass grows linearly slower, starving asyncio and breaking unrelated zeroconf consumers (discovery, registration, ServiceBrowser callbacks). A second variant \u2014 re-multicasting cached records with shifting TTLs \u2014 grows `_expire_heap` unbounded between cleanup runs without touching `cache` or `_total_records`.\n\n### Patches\n\nFixed in `zeroconf` 0.149.6 ([PR #1718](https://github.com/python-zeroconf/python-zeroconf/pull/1718)). Upgrade to `\u003e= 0.149.6`.\n\n### Workarounds\n\nThere 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.\n\n### Resources\n\n- [PR #1718](https://github.com/python-zeroconf/python-zeroconf/pull/1718), fix\n- [Issue #1715](https://github.com/python-zeroconf/python-zeroconf/issues/1715), public tracking issue\n- [RFC 6762 \u00a710](https://www.rfc-editor.org/rfc/rfc6762#section-10), [RFC 6762 \u00a711](https://www.rfc-editor.org/rfc/rfc6762#section-11), [CWE-400](https://cwe.mitre.org/data/definitions/400.html)",
"id": "BREW-homeassistant-cli-CVE-2026-47184",
"modified": "2026-09-17T17:53:52Z",
"published": "2026-08-13T16:56:27Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/python-zeroconf/python-zeroconf/security/advisories/GHSA-rfg2-pjw2-56x2"
},
{
"type": "WEB",
"url": "https://github.com/python-zeroconf/python-zeroconf/issues/1715"
},
{
"type": "WEB",
"url": "https://github.com/python-zeroconf/python-zeroconf/pull/1718"
},
{
"type": "PACKAGE",
"url": "https://github.com/python-zeroconf/python-zeroconf"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
],
"summary": "zeroconf has unbounded DNS record cache that allows LAN-local memory exhaustion via multicast flood",
"upstream": [
"GHSA-rfg2-pjw2-56x2",
"CVE-2026-47184",
"PYSEC-2026-3439"
]
}
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