Resource exhaustion in Paulsm Zeroconf
CVE-2026-48045
Zeroconf is a pure Python implementation of multicast DNS service discovery. Prior to 0.149.12, AsyncListener.handle_query_or_defer retained every truncated TC-bit incoming query, each up to _MAX_MSG_ABSOLUTE = 8966 bytes, in self._deferred[addr] and armed a per-address timer in self._timers[addr] without capping the per-address list or distinct addr keys, allowing unauthenticated hosts on the local link over UDP/5353 (224.0.0.251 / ff02::fb) to spoof sources, grow _deferred and _timers, and cause memory exhaustion and quadratic CPU burn. This issue is fixed in version 0.149.12.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.004 (29.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 30th percentile — 29.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000
Affected products
- Paulsm Zeroconf
- Python-Zeroconf — versions < 0.149.12
Weakness classification (CWE)
References
- github.com/python-zeroconf/python-zeroconf/security/advisories/GHSA-9663-mqmp-p… (Patch, Vendor Advisory)
- github.com/python-zeroconf/python-zeroconf/pull/1751 (Patch, Issue Tracking)
- github.com/python-zeroconf/python-zeroconf/commit/b22c8ff19c66c68907d220a4823c0… (Patch)
- github.com/python-zeroconf/python-zeroconf/releases/tag/0.149.12 (Release Notes)
Frequently asked questions
- What is CVE-2026-48045?
- CVE-2026-48045 is a medium-severity vulnerability in Paulsm Zeroconf, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 6.5/10. Published 2026-07-17.
- How severe is CVE-2026-48045?
- Medium severity. CVSS v3 base score is 6.5 out of 10.