7.5

CVE-2016-4864: dena h2o

Modified
Published 12-05-2017Last modified 06-08-2024

Vulnerability summary

CVE-2016-4864 is a high (CVSS 7.5) vulnerability in dena h2o. EPSS estimates a 1.80% chance of exploitation in the next 30 days, higher than 78.5% of scored vulnerabilities.

Priority
Prioritisesevere

Severe, CVSS 7.5 (NVD); no exploitation reported by the 5 checked sources; EPSS 2% (FIRST, 03-11-2026)

Source freshness unavailable

How is this decided?
CVSS score
7.5/10
010
High · v3.0 (NVD)
EPSS score
1.80%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Timeline

  1. 12-05-2017
    PublishedVulnerability first disclosed.
  2. 06-08-2024
    Last modifiedVulnerability information updated.

Description

H2O versions 2.0.3 and earlier and 2.1.0-beta2 and earlier allows remote attackers to cause a denial-of-service (DoS) via format string specifiers in a template file via fastcgi, mruby, proxy, redirect or reproxy.

CVSS metrics

2 scores · 1 source · 2 versions

EPSS trend

Probability

1.80%

Chance of exploitation in the next 30 days

Percentile

79%

Versus all other CVEs

30-day change

No change 0.00 pp

From 1.80% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.

Dena1 product
  • h2o≥ 2.0.0, ≤ 2.0.3 | 2.1.0 | 2.1.0:beta1
Kazuho oku1 product
  • h2oversions 2.0.3 and earlier | versions 2.1.0-beta2 and earlier

2 vendors · 2 products

References

2 links