Zeroconf is a pure Python implementation of multicast DNS service discovery. Prior to 0.149.16, _read_character_string and _read_string in src/zeroconf/_protocol/incoming.py advanced self.offset by attacker-declared RDLENGTH without checking it against self._data_len, allowing unauthenticated hosts on the local link over UDP/5353 (224.0.0.251 / ff02::fb) to send a TXT, HINFO, or A/AAAA record with rdlength=65535 and seed DNSCache and ServiceInfo.properties with truncated, attacker-shaped key/value or address records. This issue is fixed in version 0.149.16.
CVE-2026-48487
MEDIUMPre-NVD 5.35.3—
EchelonGraph scoreMEDIUM confidence
This medium-severity CVE scores 5.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.2%, top 89% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
Triggered by: NVD CVSS baseline
Sources: epss, secondary
5.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
- Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.3Exploit: None knownExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 5.3
- EG Score
- 5.3(medium)
- EG Risk
- 24(Track)EG Risk 24/100SSVC: Track
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity53% × 45%Exploitation0% × 40%Automatability0% × 15%Action: Routine — remediate on your standard cadence. - EPSS PROB
- 0%
- EPSS %ILE
- 11%
- KEV
- Not listed
Published
June 22, 2026
Last Modified
July 23, 2026
Advisory Details (5)
Auto-updated Jul 17, 2026Patch available. Sources: github_commit, github_pr, github_release, github.
github Patch Available
Unvalidated rdlength in record payload readers allows LAN-local cache corruption via crafted mDNS packet · Advisory · python-zeroconf/python-zeroconf · GitHub
https://github.com/python-zeroconf/python-zeroconf/security/advisories/GHSA-qc2x-6f54-m6h9github_release Patch Available
0.149.16
Patch available: python-zeroconf/python-zeroconf 0.149.16
https://github.com/python-zeroconf/python-zeroconf/releases/tag/0.149.16github_pr Patch Available
fix: bound record payload reads against rdlength overrun
Patch available: python-zeroconf/python-zeroconf 0.149.13 (PR #1756 merged 2026-05-20)
https://github.com/python-zeroconf/python-zeroconf/pull/1756generic
Security: `_read_string`/`_read_character_string` skip remaining-byte validation, enabling silent record-data corruption · Issue #1752 · python-zeroconf/python-zeroconf · GitHub
https://github.com/python-zeroconf/python-zeroconf/issues/1752github_commit Patch Available
commit 544449596e64 (python-zeroconf/python-zeroconf)
Patch available: python-zeroconf/python-zeroconf 0.149.13 (contains commit 544449596e64)
https://github.com/python-zeroconf/python-zeroconf/commit/544449596e645fcaad3834fa0cb614a54f847a82Vendor Advisories for CVE-2026-48487(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Affected Packages
(1 across 1 ecosystem)
PyPI(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| zeroconf | 0.100.0 ... 0.99.0 (259 versions) | 0.149.16 | — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 10× in last 7d / 13× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-27 06:28 UTCEG score recompute
- 2026-07-26 14:54 UTCEPSS rescore
- 2026-07-26 05:13 UTCEG score recompute
- 2026-07-25 14:18 UTCEPSS rescore
- 2026-07-24 14:18 UTCEPSS rescore
- 2026-07-23 14:18 UTCEPSS rescore
- 2026-07-23 03:18 UTCEG score recompute▼ 1.20
- 2026-07-22 14:08 UTCEPSS rescore
- 2026-07-21 15:25 UTCEPSS rescore
- 2026-07-20 17:08 UTCEPSS rescore
- 2026-07-19 14:31 UTCEPSS rescore
- 2026-07-19 02:29 UTCEPSS rescore
- 2026-07-17 18:34 UTCMITRE cvelistV5CVSS v3 → 5.3 · CVSS v4 → 5.3
- 2026-06-22 23:31 UTCEG score recompute
Frequently asked(5)
What is CVE-2026-48487?
CVE-2026-48487 is a medium vulnerability published on June 22, 2026. Zeroconf is a pure Python implementation of multicast DNS service discovery. Prior to 0.149.16, readcharacterstring and readstring in src/zeroconf/protocol/incoming.py advanced self.offset by attacker-declared RDLENGTH without checking it against self.datalen, allowing unauthenticated hosts on the…
When was CVE-2026-48487 disclosed?
CVE-2026-48487 was first published in the National Vulnerability Database on June 22, 2026, with the most recent update on July 23, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-48487 actively exploited?
CVE-2026-48487 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 89.5% of all scored CVEs.
What is the CVSS score of CVE-2026-48487?
CVE-2026-48487 has a CVSS v3 base score of 5.3 (NVD).
How do I remediate CVE-2026-48487?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-48487, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-48487
Is Your Infrastructure Affected by CVE-2026-48487?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.