How severe is CVE-2016-6306?

CVE-2016-6306 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-2016-6306 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 42% (99th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2016-6306?

CVE-2016-6306 primarily affects Openssl. In total, 47 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2016-6306?

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

When was CVE-2016-6306 published?

CVE-2016-6306 was published on 2016-09-26 and last updated on 2026-06-17.

CVE-2016-6306

CVE-2016-6306 is a medium-severity vulnerability in Openssl with a CVSS 3.x base score of 5.9. Its EPSS exploit-prediction score of 42% places it in the 99th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-125.

Key facts

Severity: Medium (CVSS 3.x base score 5.9)
CVSS v2: 4.3
EPSS exploit prediction: 42% (99th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-125
Affected product: Openssl
Published: 2016-09-26
Last modified: 2026-06-17

Description

The certificate parser in OpenSSL before 1.0.1u and 1.0.2 before 1.0.2i might allow remote attackers to cause a denial of service (out-of-bounds read) via crafted certificate operations, related to s3_clnt.c and s3_srvr.c.

Frequently asked questions

What is CVE-2016-6306?: The certificate parser in OpenSSL before 1.0.1u and 1.0.2 before 1.0.2i might allow remote attackers to cause a denial of service (out-of-bounds read) via crafted certificate operations, related to s3_clnt.c and s3_srvr.c.
How severe is CVE-2016-6306?: CVE-2016-6306 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-2016-6306 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 42% (99th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-6306?: CVE-2016-6306 primarily affects Openssl. In total, 47 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2016-6306?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2016-6306 published?: CVE-2016-6306 was published on 2016-09-26 and last updated on 2026-06-17.

References

Affected products (47)

cpe:2.3:a:openssl:openssl:1.0.1:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.1:beta1:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.1:beta2:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.1:beta3:*:*:*:*:*:*
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:hp:icewall_federation_agent:3.0:*:*:*:*:*:*:*
cpe:2.3:a:hp:icewall_mcrp:3.0:*:*:*:*:*:*:*
cpe:2.3:a:hp:icewall_sso:10.0:*:*:*:certd:*:*:*
cpe:2.3:a:hp:icewall_sso:10.0:*:*:*:dfw:*:*:*
cpe:2.3:a:hp:icewall_sso_agent_option:10.0:*:*:*:*:*:*:*
cpe:2.3:o:novell:suse_linux_enterprise_module_for_web_scripting:12.0:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.2:*:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.2:beta1:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.2:beta2:*:*:*:*:*:*
cpe:2.3:a:openssl:openssl:1.0.2:beta3:*:*:*:*:*:*
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:*:*:*:*:*:*:*

More vulnerabilities in Openssl

CVE-2009-3245 — Critical (CVSS 10.0): OpenSSL before 0.9.8m does not check for a NULL return value from bn_wexpand function calls in (1) crypto/bn/bn_div.c,…
CVE-2006-3738 — Critical (CVSS 10.0): Buffer overflow in the SSL_get_shared_ciphers function in OpenSSL 0.9.7 before 0.9.7l, 0.9.8 before 0.9.8d, and earlier…
CVE-2026-31789 — Critical (CVSS 9.8): Issue summary: Converting an excessively large OCTET STRING value to a hexadecimal string leads to a heap buffer…
CVE-2022-2274 — Critical (CVSS 9.8): The OpenSSL 3.0.4 release introduced a serious bug in the RSA implementation for X86_64 CPUs supporting the AVX512IFMA…
CVE-2021-3711 — Critical (CVSS 9.8): In order to decrypt SM2 encrypted data an application is expected to call the API function EVP_PKEY_decrypt().…
CVE-2016-6309 — Critical (CVSS 9.8): statem/statem.c in OpenSSL 1.1.0a does not consider memory-block movement after a realloc call, which allows remote…

All CVEs affecting Openssl →

Other CWE-125 (Out-of-bounds Read) vulnerabilities

CVE-2026-24826 — Critical (CVSS 10.0): Out-of-bounds Write, Divide By Zero, NULL Pointer Dereference, Use of Uninitialized Resource, Out-of-bounds Read,…
CVE-2024-22004 — Critical (CVSS 10.0): Due to length check, an attacker with privilege access on a Linux Nonsecure operating system can trigger a…
CVE-2021-41556 — Critical (CVSS 10.0): sqclass.cpp in Squirrel through 2.2.5 and 3.x through 3.1 allows an out-of-bounds read (in the core interpreter) that…
CVE-2021-21777 — Critical (CVSS 10.0): An information disclosure vulnerability exists in the Ethernet/IP UDP handler functionality of EIP Stack Group OpENer…
CVE-2017-14451 — Critical (CVSS 10.0): An exploitable out-of-bounds read vulnerability exists in libevm (Ethereum Virtual Machine) of CPP-Ethereum. A…
CVE-2013-0767 — Critical (CVSS 10.0): The nsSVGPathElement::GetPathLengthScale function in Mozilla Firefox before 18.0, Firefox ESR 10.x before 10.0.12 and…

Browse all CWE-125 (Out-of-bounds Read) vulnerabilities →

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)