No exploitation reportedFix available

CVE-2016-6303

Q: Is CVE-2016-6303 actively exploited?

Active exploitation of CVE-2016-6303 has not been confirmed. Its EPSS score was 32.0% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2016-6303?

CVE-2016-6303 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

No exploitation reported by the sources we read.

Published2016-09-16
WeaknessCWE-787

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC

2016-09-1605:59CVE publishedNVD
2026-10-2319:23EPSS crossed 10 %FIRST EPSS

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2016-6303?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2016-6303?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

OpenSSL

Branch	Affected	Fixed in	Source
1.0	= 1.0.1	no fix published	NVD
1.0	= 1.0.1a	no fix published	NVD
1.0	= 1.0.1b	no fix published	NVD
1.0	= 1.0.1c	no fix published	NVD
1.0	= 1.0.1d	no fix published	NVD
1.0	= 1.0.1e	no fix published	NVD
1.0	= 1.0.1f	no fix published	NVD
1.0	= 1.0.1g	no fix published	NVD
1.0	= 1.0.1h	no fix published	NVD
1.0	= 1.0.1i	no fix published	NVD
1.0	= 1.0.1j	no fix published	NVD
1.0	= 1.0.1k	no fix published	NVD

Node.js

Branch	Affected	Fixed in	Source
6.x	≥ 6.0.0, < 6.6.0	6.6.0	NVD
4.x	≥ 4.0.0, < 4.6.0	4.6.0	NVD
0.12	< 0.12.16	0.12.16	NVD

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Advisories and patches

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVSS 3.19.8read 2026-10-23
NVDCVSS 2.07.5read 2026-10-23
NVDweakness (CWE)CWE-787read 2026-10-23
FIRST EPSSEPSS score32.0 %read 2026-10-23

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published: 2016-09-16
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2016-6303?

Is CVE-2016-6303 actively exploited?

Active exploitation of CVE-2016-6303 has not been confirmed. Its EPSS score was 32.0% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2016-6303?

CVE-2016-6303 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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