CVE-2016-6559

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2022-05-13. NVD baseline CVSS 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 4%CVSS: 9.8Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Improper bounds checking of the obuf variable in the link_ntoa() function in linkaddr.c of the BSD libc library may allow an attacker to read or write from memory. The full impact and severity depends on the method of exploit and how the library is used by applications. According to analysis by FreeBSD developers, it is very unlikely that applications exist that utilize link_ntoa() in an exploitable manner, and the CERT/CC is not aware of any proof of concept. A blog post describes the functionality of link_ntoa() and points out that none of the base utilities use this function in an exploitable manner. For more information, please see FreeBSD Security Advisory SA-16:37.

CVSS v3
9.8
EG Score
9.8(medium)
EPSS
88.5%
KEV
Not listed

Published

July 13, 2018

Last Modified

November 21, 2024

Advisory Details (4)

Auto-updated May 28, 2026
🔬 Proof of concept available. No patch confirmed yet. Sources: cert.
generic
https://www.securityfocus.com/bid/94694
cert🟡 PoC Available

VU#548487 - BSD libc contains a buffer overflow vulnerability in link_ntoa()

https://www.kb.cert.org/vuls/id/548487
generic
https://www.freebsd.org/security/advisories/FreeBSD-SA-16:37.libc.asc
generic
http://www.securitytracker.com/id/1037398

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 9× in last 7d / 36× 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.

  1. 2026-07-16 16:59 UTCEPSS rescore
  2. 2026-07-16 16:59 UTCEPSS rescore
  3. 2026-07-15 16:54 UTCEPSS rescore
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  5. 2026-07-15 01:56 UTCEPSS rescore
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  7. 2026-07-12 05:43 UTCEPSS rescore
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  10. 2026-07-09 19:06 UTCEPSS rescore
  11. 2026-07-08 15:10 UTCEPSS rescore
  12. 2026-07-07 13:42 UTCEPSS rescore
  13. 2026-07-06 16:24 UTCEPSS rescore
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  15. 2026-07-06 02:20 UTCEPSS rescore
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  17. 2026-07-05 02:27 UTCEPSS rescore
  18. 2026-07-04 06:28 UTCEPSS rescore
  19. 2026-07-01 15:02 UTCEPSS rescore
  20. 2026-06-30 23:19 UTCEPSS rescore
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  22. 2026-06-29 14:03 UTCEPSS rescore
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  24. 2026-06-28 04:53 UTCEPSS rescore
  25. 2026-06-27 03:05 UTCEPSS rescore
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  1. 2026-06-25 13:47 UTCEPSS rescore
  2. 2026-06-24 14:02 UTCEPSS rescore
  3. 2026-06-23 21:30 UTCEPSS rescore
  4. 2026-06-21 14:54 UTCEPSS rescore
  5. 2026-06-21 14:54 UTCEPSS rescore
  6. 2026-06-21 01:57 UTCEPSS rescore
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  8. 2026-06-18 17:50 UTCEPSS rescore
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  10. 2026-06-17 17:50 UTCEPSS rescore
  11. 2026-06-17 17:50 UTCEPSS rescore
  12. 2026-06-16 17:50 UTCEPSS rescore
  13. 2026-06-15 17:45 UTCEPSS rescore
  14. 2026-06-14 23:14 UTCEPSS rescore
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  16. 2026-06-13 22:57 UTCEPSS rescore
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  18. 2026-06-12 23:09 UTCEPSS rescore
  19. 2026-06-11 13:57 UTCEPSS rescore
  20. 2026-06-08 14:14 UTCEPSS rescore
  21. 2026-06-05 22:44 UTCEPSS rescore
  22. 2026-06-05 06:08 UTCEPSS rescore
  23. 2026-06-05 06:08 UTCEPSS rescore
  24. 2026-06-04 13:10 UTCEPSS rescore
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  26. 2026-06-02 20:10 UTCEPSS rescore
  27. 2026-06-01 13:49 UTCEPSS rescore
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  29. 2026-05-31 22:28 UTCEPSS rescore
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  31. 2026-05-31 00:14 UTCEPSS rescore
  32. 2026-05-29 13:41 UTCEPSS rescore
  33. 2026-05-28 13:42 UTCEPSS rescore
  34. 2026-05-28 13:42 UTCEPSS rescore
  35. 2026-05-28 05:14 UTCEG score recompute
  36. 2026-05-28 05:14 UTCGHSA enrichment
  37. 2026-05-27 13:38 UTCEPSS rescore
  38. 2026-05-27 13:38 UTCEPSS rescore
  39. 2026-05-26 13:42 UTCEPSS rescore
  40. 2026-05-26 13:42 UTCEPSS rescore
  41. 2026-05-26 07:17 UTCEPSS rescore
  42. 2026-05-24 16:44 UTCEPSS rescore

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Frequently asked(5)

What is CVE-2016-6559?
CVE-2016-6559 is a critical vulnerability published on July 13, 2018. Improper bounds checking of the obuf variable in the linkntoa() function in linkaddr.c of the BSD libc library may allow an attacker to read or write from memory. The full impact and severity depends on the method of exploit and how the library is used by applications. According to analysis by…
When was CVE-2016-6559 disclosed?
CVE-2016-6559 was first published in the National Vulnerability Database on July 13, 2018, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2016-6559 actively exploited?
CVE-2016-6559 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 88.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2016-6559?
CVE-2016-6559 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2016-6559?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2016-6559, 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.

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