CVE-2023-50247

HIGH EPSS 53.8%
Published Dec 12, 20232y ago · Modified Jun 17, 20262w ago
7.5 CVSS 3.1
High
Find Similar
Published Dec 12, 2023 2y ago
Last Modified Jun 17, 2026 2w ago

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.

CVSS Details

Base Score
7.5
Exploitability
3.9
Impact
3.6
Vector string
CVSS:3.1/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 None
Integrity None
Availability High

Threat Intelligence

EPSS Exploit Probability
53.8% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-770

Affected Products 3

VendorProductVersionRange
denah2o* ≤2.2.6
denah2o2.3.0any
denah2o2.3.0any

References 2

  • github.com https://github.com/h2o/h2o/commit/d67e81d03be12a9d53dc8271af6530f40164cd35
    Patch
  • github.com https://github.com/h2o/h2o/security/advisories/GHSA-2ch5-p59c-7mv6
    PatchVendor Advisory

Remediation

  • github.com https://github.com/h2o/h2o/commit/d67e81d03be12a9d53dc8271af6530f40164cd35
    Patch
  • github.com https://github.com/h2o/h2o/security/advisories/GHSA-2ch5-p59c-7mv6
    PatchVendor Advisory