Predictive Vulnerability Intelligence.

Product

  • Product
  • Pricing
  • Documentation

Company

  • About
  • Partnerships
  • Blog
  • Support

Legal

  • Terms
  • Privacy
  • Data Licensing

© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2024-45403

22
FAUCET Score

CVE-2024-45403 is a Denial-of-Service vulnerability affecting the h2o HTTP server when configured as a reverse proxy and handling HTTP/3 requests. A remote attacker can trigger an assertion failure and crash the server by cancelling HTTP/3 requests, disrupting concurrent HTTP traffic. Rated 7.5 HIGH (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H), this vulnerability is easily exploitable with low attack complexity and no user interaction required. While the standalone server typically restarts, the issue is patched in commit 1ed32b2, and disabling HTTP/3 is a viable mitigation; there is currently no evidence of active exploitation, public exploit code, or significant community discussion.

Impacted Technologies

VendorProductVersion(s)CPE
>= 2024-06-18, < 2024-09-04CPE matchmatch criteria
cpe:2.3:a:dena:h2o:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

3.7LOW

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
LOW
Exploitability Score
2.2
Impact Score
1.4
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.66%
Probability of exploitation in next 30 days
EPSS Percentile
47.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0066 is in the 24th percentile among its peer group of 51,551 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

github_advisorypatch availablevia nvd_reference
View patch

References

github.com / h2o/h2o/commit/16b13eee8ad7895b4fe3fcbcabee53bd52782562
Patch
github.com / h2o/h2o/commit/1ed32b23f999acf0c5029f09c8525f93eb1d354c
Patch
github.com / h2o/h2o/security/advisories/GHSA-4xp5-3jhc-3m92
Vendor Advisory
h2o.examp1e.net / configure/http3_directives.html
Product