8.2

CVE-2023-30847: H2O vulnerable to read from uninitialized pointer in the reverse proxy handler

Modified
AliasesUBUNTU-CVE-2023-30847
Published 27-04-2023Last modified 30-01-2025

Vulnerability summary

CVE-2023-30847 is a high (CVSS 8.2) Access of Uninitialized Pointer vulnerability in dena h2o. EPSS estimates a 0.90% chance of exploitation in the next 30 days, higher than 59.7% of scored vulnerabilities.

Priority
Prioritisesevere

Severe, CVSS 8.2 (CVE.org); no exploitation reported by the 5 checked sources; EPSS 1% (FIRST, 03-11-2026)

Source freshness unavailable

How is this decided?
CVSS score
8.2/10
010
High · v3.1 (CVE.org)
EPSS score
0.90%
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. 27-04-2023
    PublishedVulnerability first disclosed.
  2. 30-01-2025
    Last modifiedVulnerability information updated.

Description

H2O is an HTTP server. In versions 2.3.0-beta2 and prior, when the reverse proxy handler tries to processes a certain type of invalid HTTP request, it tries to build an upstream URL by reading from uninitialized pointer. This behavior can lead to crashes or leak of information to back end HTTP servers. Pull request number 3229 fixes the issue. The pull request has been merged to the `master` branch in commit f010336. Users should upgrade to commit f010336 or later.

CVSS metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.90%

Chance of exploitation in the next 30 days

Percentile

60%

Versus all other CVEs

30-day change

No change 0.00 pp

From 0.90% 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≤ 2.2.6 | 2.3.0:beta1 | 2.3.0:beta2
H2o1 product
  • h2o≤ 2.3.0-beta2
Ubuntu1 product
  • h2oAll versions (No fix recorded)

3 vendors · 3 products

References

5 links