HOMEVULNERABILITIESCVE-2023-50247
HIGH

CVE-2023-50247

CWE-770Published: December 12, 2023· Updated: Jun 17, 2026

7.5
CVSS v3.1

Official Description

h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. The QUIC stack (quicly), as used by H2O up to commit 43f86e5 (in version 2.3.0-beta and prior), is susceptible to a state exhaustion attack. When H2O is serving HTTP/3, a remote attacker can exploit this vulnerability to progressively increase the memory retained by the QUIC stack. This can eventually cause H2O to abort due to memory exhaustion. The vulnerability has been resolved in commit d67e81d03be12a9d53dc8271af6530f40164cd35. HTTP/1 and HTTP/2 are not affected by this vulnerability as they do not use QUIC. Administrators looking to mitigate this issue without upgrading can disable HTTP/3 support.

NVD Source

Technical Analysis

CVE-2023-50247 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in availability disruption (denial of service), with a CVSS base score of 7.5.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityNone
IntegrityNone
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected Vendors & Products

dena1 product(s)
h2o
Source: NVD CPE · 2 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttps://github.com/h2o/h2o/commit/d67e81d03be12a9d53dc8271af6530f40164cd35
PATCHhttps://github.com/h2o/h2o/security/advisories/GHSA-2ch5-p59c-7mv6
PATCHhttps://github.com/h2o/h2o/commit/d67e81d03be12a9d53dc8271af6530f40164cd35
PATCHhttps://github.com/h2o/h2o/security/advisories/GHSA-2ch5-p59c-7mv6

All References (4)

→
https://github.com/h2o/h2o/commit/d67e81d03be12a9d53dc8271af6530f40164cd35Patch
→
https://github.com/h2o/h2o/security/advisories/GHSA-2ch5-p59c-7mv6Patch · Vendor Advisory
→
https://github.com/h2o/h2o/commit/d67e81d03be12a9d53dc8271af6530f40164cd35Patch
→
https://github.com/h2o/h2o/security/advisories/GHSA-2ch5-p59c-7mv6Patch · Vendor Advisory

Quick Facts

CVE IDCVE-2023-50247
CVSS Score7.5 / 10
SeverityHIGH
WeaknessCWE-770
CISA KEVNo
Affected1 vendor(s)
PublishedDec 12, 2023

Related CVEs (CWE-770)

CVE-2023-38507
9.8
CVE-2023-25156
9.8
CVE-2019-17067
9.8
CVE-2022-3439
9.8
CVE-2022-3273
9.8
CVE-2018-20033
9.8

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2023-50247 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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