What is CVE-2016-4303?

CVE-2016-4303 is a critical-severity vulnerability in Es Iperf3, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 9.8/10. Published 2016-09-26.

How severe is CVE-2016-4303?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Buffer overflow in Es Iperf3

CVE-2016-4303

The parse_string function in cjson.c in the cJSON library mishandles UTF8/16 strings, which allows remote attackers to cause a denial of service (crash) or execute arbitrary code via a non-hex character in a JSON string, which triggers a heap-based buffer overflow.

Vulnerability class: Buffer Overflow

Published 2016-09-26 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.070 (94.1th percentile), scored 2026-10-20.

Low probability of exploitation in the next 30 days, but still tracked. 94th percentile — 94.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.070 · newest: 0.070 · change: 0.000

Affected products

Es Iperf3
Novell SUSE Package Hub For Linux Enterprise — versions 12
Debian Linux — versions 8.0
openSUSE Leap — versions 42.1
openSUSE — versions 13.2

Weakness classification (CWE)

CWE-120 — Buffer Copy without Checking Size of Input (Classic Buffer Overflow)

References

www.talosintelligence.com/reports/TALOS-2016-0164/ (Exploit, Third Party Advisory)
blog.talosintel.com/2016/06/esnet-vulnerability.html (Exploit, Third Party Advisory)
software.es.net/iperf/news.html (Third Party Advisory, Release Notes)
raw.githubusercontent.com/esnet/security/master/cve-2016-4303/esnet-secadv-2016… (Third Party Advisory)
github.com/esnet/iperf/commit/91f2fa59e8ed80dfbf400add0164ee0e508e412a (Patch, Third Party Advisory)
lists.opensuse.org/opensuse-updates/2016-08/msg00082.html (vendor-advisory, Mailing List, Third Party Advisory)
lists.opensuse.org/opensuse-updates/2016-08/msg00090.html (vendor-advisory, Mailing List, Third Party Advisory)
lists.debian.org/debian-lts-announce/2020/01/msg00023.html (mailing-list, Mailing List, Third Party Advisory)

Frequently asked questions

What is CVE-2016-4303?: CVE-2016-4303 is a critical-severity vulnerability in Es Iperf3, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 9.8/10. Published 2016-09-26.
How severe is CVE-2016-4303?: Critical severity. CVSS v3 base score is 9.8 out of 10.