python-zeroconf: Unbounded TC-deferred queue allows LAN-local memory exhaustion via spoofed-source flood

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

6.5 · CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

• CVE-2026-48045: 0.37% estimated exploitation activity in the next 30 days; percentile 30.98 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact AsyncListener.handlequeryordefer 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. Any 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 MAXMSGABSOLUTE = 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…

Published by the source

11 Jun 2026, 13:28 UTC

Last modified by the source

13 Jul 2026, 16:43 UTC

Source last checked

26 Oct 2026, 13:45 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-9663-mqmp-p9mm

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-9663-mqmp-p9mm

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-48045

Advisory: python-zeroconf: Unbounded TC-deferred queue allows LAN-local memory exhaustion via spoofed-source flood
IDs: CVE-2026-48045, GHSA-9663-mqmp-p9mm
Record: https://patchnext.com/advisories/cve-2026-48045 (revision 2, source checked 26 Oct 2026, 13:45 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: zeroconf 0.149.12. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI zeroconf: affected < 0.149.12; fixed in 0.149.12

## Suggested inspection (read-only)
- `python -m pip show zeroconf`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on zeroconf.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-9663-mqmp-p9mm (OSV record GHSA-9663-mqmp-p9mm lists affected ranges: PyPI zeroconf >=0 <0.149.12 (fixed))
- Verified: https://github.com/advisories/GHSA-9663-mqmp-p9mm (GitHub-reviewed advisory GHSA-9663-mqmp-p9mm lists affected ranges: PyPI zeroconf >=0 <0.149.12)

Commands are suggestions: review each one before running it.