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CVE-2016-4864

24
FAUCET Score

CVE-2016-4864 describes a denial-of-service (DoS) vulnerability affecting H2O versions 2.0.3 and earlier, and 2.1.0-beta2 and earlier. Remote attackers can trigger this DoS by injecting format string specifiers into template files through various H2O functionalities like fastcgi, mruby, proxy, redirect, or reproxy. With a CVSS v3.0 score of 7.5 (HIGH), this vulnerability is easily exploitable over the network with low attack complexity, requiring no user interaction, and leading to a complete loss of availability. There is no evidence of active exploitation, publicly available exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
>= 2.0.0, <= 2.0.3CPE matchmatch criteria
cpe:2.3:a:dena:h2o:*:*:*:*:*:*:*:*
2.1.0CPE matchmatch criteria
cpe:2.3:a:dena:h2o:2.1.0:*:*:*:*:*:*:*
2.1.0CPE matchmatch criteria
cpe:2.3:a:dena:h2o:2.1.0:beta1:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

7.5HIGH

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.0

Exploit Intelligence

EPSS Score
1.80%
Probability of exploitation in next 30 days
EPSS Percentile
76.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-24
Model: v2026.06.15
This CVE's current EPSS score of 0.0180 is in the 59th percentile among its peer group of 51,455 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

github_advisorypatch availablevia nvd_reference
View patch

References

github.com / h2o/h2o/issues/1077
PatchThird Party Advisory
jvn.jp / en/jp/JVN94779084/index.html
Third Party AdvisoryVDB Entry