How severe is CVE-2016-6307?

CVE-2016-6307 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2016-6307 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 14% (96th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2016-6307?

CVE-2016-6307 affects Openssl. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2016-6307?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2016-6307 published?

CVE-2016-6307 was published on 2016-09-26 and last updated on 2026-06-17.

CVE-2016-6307

CVE-2016-6307 is a medium-severity vulnerability in Openssl with a CVSS 3.x base score of 5.9. Its EPSS exploit-prediction score of 14% places it in the 96th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-400.

Key facts

Severity: Medium (CVSS 3.x base score 5.9)
CVSS v2: 4.3
EPSS exploit prediction: 14% (96th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-400
Affected product: Openssl
Published: 2016-09-26
Last modified: 2026-06-17

Description

The state-machine implementation in OpenSSL 1.1.0 before 1.1.0a allocates memory before checking for an excessive length, which might allow remote attackers to cause a denial of service (memory consumption) via crafted TLS messages, related to statem/statem.c and statem/statem_lib.c.

Frequently asked questions

What is CVE-2016-6307?: The state-machine implementation in OpenSSL 1.1.0 before 1.1.0a allocates memory before checking for an excessive length, which might allow remote attackers to cause a denial of service (memory consumption) via crafted TLS messages, related to statem/statem.c and statem/statem_lib.c.
How severe is CVE-2016-6307?: CVE-2016-6307 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2016-6307 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 14% (96th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-6307?: CVE-2016-6307 affects Openssl. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2016-6307?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2016-6307 published?: CVE-2016-6307 was published on 2016-09-26 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:openssl:openssl:1.1.0:*:*:*:*:*:*:*

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