CVE-2026-47184 | Zeroconf: Unbounded DNS record cache allows LAN-local memory exhaustion via multicast flood

Zeroconf is a pure Python implementation of multicast DNS service discovery. Prior to 0.149.7, DNSCache._async_add inserted every response record into cache, _expirations, _expire_heap, and service_cache without a cap, allowing unauthenticated hosts on the local link over UDP/5353 (224.0.0.251 / ff02::fb) to multicast valid mDNS responses with unique names and cause memory exhaustion, slower cache lookups, slower async_expire passes, and broken discovery, registration, and ServiceBrowser callbacks. This issue is fixed in version 0.149.7.

Published: 2026-07-17 Last update: 2026-07-23 Assigner: [email protected] Source: [email protected]
NVD Status：Awaiting Analysis，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-47184 is rated Low Risk (31.6/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.24%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-47184

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-07-18 0.02% 0.24% +0.22%
2 2026-06-12 — 0.02% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-47184

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:A)
Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.8 3.6 [email protected]

Weakness enumeration for CVE-2026-47184

GitHub Security Advisory for CVE-2026-47184

GHSA-rfg2-pjw2-56x2 · Severity: medium · Ecosystem: pip — zeroconf has unbounded DNS record cache that allows LAN-local memory exhaustion via multicast flood

OS Trackers for CVE-2026-47184

vendor priority summary link
debian not yet assigned CVE-2026-47184 not yet assigned priority: Debian including 1 source packages (python-zeroconf), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): open 3, resolved 2. https://security-tracker.debian.org/tracker/CVE-2026-47184
suse medium — https://www.suse.com/security/cve/CVE-2026-47184/
ubuntu medium CVE-2026-47184 medium priority: Ubuntu including 1 source packages (python-zeroconf), 6 status rows across 6 suites (bionic, focal, jammy, noble, resolute, upstream): needs-triage 5, released 1. https://ubuntu.com/security/CVE-2026-47184

Affected software / configurations for CVE-2026-47184

Vendor Product Version Raw CPE
No affected products in dataset.

References for CVE-2026-47184

cvelogic Threat Intelligence