Skip to main content
No exploitation reportedFix available

CVE-2024-45403

No exploitation reported by the sources we read.

  • Published2024-10-11
  • Fixed in2024-09-04
  • WeaknessCWE-617

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. When h2o is configured as a reverse proxy and HTTP/3 requests are cancelled by the client, h2o might crash due to an assertion failure. The crash can be exploited by an attacker to mount a Denial-of-Service attack. By default, the h2o standalone server automatically restarts, minimizing the impact. However, HTTP requests that were served concurrently will still be disrupted. The vulnerability has been addressed in commit 1ed32b2. Users may disable the use of HTTP/3 to mitigate the issue.

Timeline

dates in UTC
  1. 2024-10-1115:15CVE publishedNVD

Versions per branch

NVD
Dena h2o
BranchAffectedFixed in
2024.x≥ 2024-06-18, < 2024-09-042024-09-04

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Products declared by the CNA1 product

As GitHub_M, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

  • h2o
    Affected
    • = >= 16b13eee8ad7895b4fe3fcbcabee53bd52782562, < 1ed32b23f999acf0c5029f09c8525f93eb1d354cno fix stated

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2024-10-11

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • h2oUbuntu:Pro:22.04:LTSall versions · no fixed version listed
  • h2oUbuntu:Pro:20.04:LTSall versions · no fixed version listed
  • h2oUbuntu:Pro:18.04:LTSall versions · no fixed version listed
  • h2oUbuntu:24.04:LTSall versions · no fixed version listed

Full record on NVD

Fix

  1. Update Dena h2o to 2024-09-04

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

  • CISA-ADPSSVC decisionnone2024-10-11
  • CNACVSS 3.13.7known since 2026-10-23
  • NVDCVSS 3.17.5read 2026-10-23
  • CNAweakness (CWE)CWE-617known since 2026-10-23
  • FIRST EPSSEPSS score0.7 %2026-11-09
  • OSVaffected packages—

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published
2024-10-11
Last Modified
2026-06-17
NVD status
Analyzed

Frequently asked questions

What is CVE-2024-45403?

h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. When h2o is configured as a reverse proxy and HTTP/3 requests are cancelled by the client, h2o might crash due to an assertion failure. The crash can be exploited by an attacker to mount a Denial-of-Service attack. By default, the h2o standalone server automatically restarts, minimizing the impact. However, HTTP requests that were served concurrently will still be disrupted. The vulnerability has been addressed in commit 1ed32b2. Users may disable the use of HTTP/3 to mitigate the issue.

Is CVE-2024-45403 actively exploited?

Active exploitation of CVE-2024-45403 has not been confirmed. Its EPSS score was 0.7% on 2026-11-09, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2024-45403?

CVE-2024-45403 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Running h2o? Hear about its next vulnerability

Surveillance reads the versions in your stack — a domain, a lockfile or a list — checks each CVE against the ranges its sources publish, and alerts you when one you run is exploited or enters CISA KEV. A version it cannot read stays « version not verified ».

Get alerts for this productCISA KEV additions, November 2026Search CVEs

No credit card required · No monthly cap on website lookups · 250 API requests/month

Go further

Related vulnerabilities

Same product first, then the same vendor advisory and the same publication week.

Back to CVE Database

Sources for this record