How severe is CVE-2016-4303?

CVE-2016-4303 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2016-4303 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 7% (93rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2016-4303?

CVE-2016-4303 primarily affects Es Iperf3. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2016-4303?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2016-4303 published?

CVE-2016-4303 was published on 2016-09-26 and last updated on 2026-06-17.

CVE-2016-4303

CVE-2016-4303 is a critical-severity vulnerability in Es Iperf3 with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-120.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 7% (93rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-120
Affected product: Es Iperf3
Published: 2016-09-26
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is 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.
How severe is CVE-2016-4303?: CVE-2016-4303 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2016-4303 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 7% (93rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-4303?: CVE-2016-4303 primarily affects Es Iperf3. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2016-4303?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2016-4303 published?: CVE-2016-4303 was published on 2016-09-26 and last updated on 2026-06-17.

References

Affected products (5)

cpe:2.3:a:es:iperf3:*:*:*:*:*:*:*:*
cpe:2.3:a:novell:suse_package_hub_for_suse_linux_enterprise:12:*:*:*:*:*:*:*
cpe:2.3:o:opensuse:leap:42.1:*:*:*:*:*:*:*
cpe:2.3:o:opensuse:opensuse:13.2:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*

More vulnerabilities in Es Iperf3

CVE-2025-54351 — High (CVSS 8.9): In iperf before 3.19.1, net.c has a buffer overflow when --skip-rx-copy is used (for MSG_TRUNC in recv).
CVE-2024-53580 — High (CVSS 7.5): iperf v3.17.1 was discovered to contain a segmentation violation via the iperf_exchange_parameters() function.
CVE-2023-38403 — High (CVSS 7.5): iperf3 before 3.14 allows peers to cause an integer overflow and heap corruption via a crafted length field.
CVE-2025-54349 — Medium (CVSS 6.5): In iperf before 3.19.1, iperf_auth.c has an off-by-one error and resultant heap-based buffer overflow.
CVE-2024-26306 — Medium (CVSS 5.9): iPerf3 before 3.17, when used with OpenSSL before 3.2.0 as a server with RSA authentication, allows a timing side…
CVE-2023-7250 — Medium (CVSS 5.3): A flaw was found in iperf, a utility for testing network performance using TCP, UDP, and SCTP. A malicious or…

All CVEs affecting Es Iperf3 →

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