zeroconf has unbounded recursion in DNS compression-pointer decoder that allows LAN-local denial of service
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.
Fixed in zeroconf 0.149.5 (PR #1719).
Upgrade to >= 0.149.5.
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.
왜 이 VPI인가 (설명가능 · 실험적)
VPI 산정 기준
| 영향도 | 65.00 |
| 악용 신호(추가 악용신호 없음) | ×1.00 |
| VPI | 65.00 |
VPI 공식 vpi-v1 기준
| 소스 | CVSS 버전 | 기본 점수 | 심각도 | 벡터 문자열 | 평가일 |
|---|---|---|---|---|---|
| NVDNIST | 3.1 | 6.5 | MEDIUM | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | 2026. 07. 18. |
| OSV3rd | 3.1 | 6.5 |
| CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| 2026. 05. 30. |