H2O Server Certificate use after free

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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A vulnerability was found in H2O (affected version unknown). It has been declared as critical. Affected by this vulnerability is an unknown function of the component Server Certificate. The manipulation with an unknown input leads to a use after free vulnerability. The CWE definition for the vulnerability is CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

Use-after-free vulnerability in H2O allows remote attackers to cause a denial-of-service (DoS) or obtain server certificate private keys and possibly other information.

The bug was discovered 12/22/2016. The weakness was presented 06/09/2017 (Website). The advisory is shared at jvn.jp. This vulnerability is known as CVE-2016-7835 since 09/09/2016. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Neither technical details nor an exploit are publicly available.

The vulnerability was handled as a non-public zero-day exploit for at least 169 days. During that time the estimated underground price was around $0-$5k.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.



CPE 2.3info

CPE 2.2info


VulDB Meta Base Score: 8.2
VulDB Meta Temp Score: 8.2

VulDB Base Score: 7.3
VulDB Temp Score: 7.3
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 9.1
NVD Vector: 🔍



VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

NVD Base Score: 🔍


Class: Use after free
CWE: CWE-416 / CWE-119
ATT&CK: Unknown

Local: No
Remote: Yes

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍


OpenVAS ID: 800452
OpenVAS Name: H2O HTTP Server DoS Vulnerability
OpenVAS File: 🔍
OpenVAS Family: 🔍

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍


Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔍


09/09/2016 🔍
12/22/2016 +104 days 🔍
12/22/2016 +0 days 🔍
06/09/2017 +169 days 🔍
06/09/2017 +0 days 🔍
06/10/2017 +1 days 🔍
12/08/2022 +2007 days 🔍


Advisory: 1144
Researcher: Kazuho Oku.
Status: Not defined
Confirmation: 🔍

CVE: CVE-2016-7835 (🔍)
SecurityFocus: 95061 - H2O CVE-2016-7835 Use After Free Denial of Service Vulnerability


Created: 06/10/2017 08:56 AM
Updated: 12/08/2022 10:39 AM
Changes: 06/10/2017 08:56 AM (62), 10/15/2019 06:49 PM (3), 12/26/2020 06:45 PM (2), 12/08/2022 10:39 AM (2)
Complete: 🔍


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