{"id":"CVE-2026-48045","aliases":["GHSA-9663-mqmp-p9mm"],"title":"python-zeroconf: Unbounded TC-deferred queue allows LAN-local memory exhaustion via spoofed-source flood","summary":"python-zeroconf: Unbounded TC-deferred queue allows LAN-local memory exhaustion via spoofed-source flood","severity":"medium","cvss":6.5,"cwe":["CWE-400","CWE-770"],"vendor":"zeroconf","product":"zeroconf","ecosystem":"pip","affected":["zeroconf < 0.149.12"],"patched":["zeroconf 0.149.12"],"published":"2026-06-11","updated":"2026-06-11","source":"GHSA","sourceUrl":"https://github.com/advisories/GHSA-9663-mqmp-p9mm","references":[{"url":"https://github.com/python-zeroconf/python-zeroconf/security/advisories/GHSA-9663-mqmp-p9mm"},{"url":"https://github.com/python-zeroconf/python-zeroconf/pull/1751"},{"url":"https://github.com/python-zeroconf/python-zeroconf/commit/b22c8ff19c66c68907d220a4823c0950f4fa93f7"},{"url":"https://github.com/advisories/GHSA-9663-mqmp-p9mm"}],"tags":["ghsa","pip"],"ingestedAt":"2026-07-07T15:41:59.306Z","epss":0.0037,"epssPercentile":0.30892,"slug":"CVE-2026-48045","body":"## Overview\n\n### Impact\n\n`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.\n\nAny 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).\n\n### Patches\n\nFixed in `zeroconf` 0.149.12 ([PR #1751](https://github.com/python-zeroconf/python-zeroconf/pull/1751)). Upgrade to `>= 0.149.12`.\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 #1751](https://github.com/python-zeroconf/python-zeroconf/pull/1751), fix\n- [RFC 6762 §18.5](https://www.rfc-editor.org/rfc/rfc6762#section-18.5), [CWE-400](https://cwe.mitre.org/data/definitions/400.html)\n\n## Affected packages\n\n- `zeroconf < 0.149.12`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `zeroconf 0.149.12`","depth":"sunlit","depthScore":36,"depthScoreParts":{"impact":35.8,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}