How severe is CVE-2016-6303?

CVE-2016-6303 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-2016-6303 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 32% (98th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2016-6303?

CVE-2016-6303 primarily affects Nodejs Node.js. In total, 31 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2016-6303?

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-2016-6303 published?

CVE-2016-6303 was published on 2016-09-16 and last updated on 2026-06-17.

CVE-2016-6303

CVE-2016-6303 is a critical-severity vulnerability in Nodejs Node.js with a CVSS 3.x base score of 9.8. Its EPSS exploit-prediction score of 32% places it in the 98th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-787.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 32% (98th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-787
Affected product: Nodejs Node.js
Published: 2016-09-16
Last modified: 2026-06-17

Description

Integer overflow in the MDC2_Update function in crypto/mdc2/mdc2dgst.c in OpenSSL before 1.1.0 allows remote attackers to cause a denial of service (out-of-bounds write and application crash) or possibly have unspecified other impact via unknown vectors.

Frequently asked questions

What is CVE-2016-6303?: Integer overflow in the MDC2_Update function in crypto/mdc2/mdc2dgst.c in OpenSSL before 1.1.0 allows remote attackers to cause a denial of service (out-of-bounds write and application crash) or possibly have unspecified other impact via unknown vectors.
How severe is CVE-2016-6303?: CVE-2016-6303 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-2016-6303 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 32% (98th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-6303?: CVE-2016-6303 primarily affects Nodejs Node.js. In total, 31 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2016-6303?: 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-2016-6303 published?: CVE-2016-6303 was published on 2016-09-16 and last updated on 2026-06-17.

References

Affected products (31)

cpe:2.3:a:nodejs:node.js:*:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.1:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.1a:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.1b:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.1c:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.1d:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.1e:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.1f:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.1g:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.1h:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.1i:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.1j:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.1k:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.1l:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.1m:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.1n:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.1o:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.1p:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.1q:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.1r:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.1s:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.1t:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.2:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.2a:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.2b:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.2c:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.2d:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.2e:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.2f:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.2g:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.2h:*:*:*:*:*:*:*

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Threat intelligence

Threat-intel indicators referencing this CVE:

218.4.91.163 (ipv4-addr)
200.77.172.159 (ipv4-addr)
200.196.50.91 (ipv4-addr)
166.62.41.190 (ipv4-addr)
50.62.22.47 (ipv4-addr)
191.101.33.225 (ipv4-addr)
111.68.102.19 (ipv4-addr)
122.3.106.113 (ipv4-addr)