CVE catalog

CVE-2024-45403

h2o: CVE-2024-45403

Severity: Low
Published: Oct 11, 2024, 3:15:00 PM UTC
Source: [NVD] · [CVE record]
EPSS: 0.65% · Oct 25, 2026

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.

Vulnerable and fixed packages

Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.

Distribution	Package	Release	Version	Status
Debian	h2o	bookworm	`2.2.5+dfsg2-7`	not affected
Ubuntu	h2o	pro	`2.2.5+dfsg2-6`	vulnerable
Ubuntu	h2o	pro	`2.2.5+dfsg2-6.1`	vulnerable
Ubuntu	h2o	pro	`2.2.5+dfsg2-6.1ubuntu1`	vulnerable
Ubuntu	h2o	pro	`2.2.5+dfsg2-6.1ubuntu2`	vulnerable
Ubuntu	h2o	pro	`2.2.5+dfsg2-6.1ubuntu2+esm1`	vulnerable
Ubuntu	h2o	24.04	`2.2.5+dfsg2-7`	vulnerable
Ubuntu	h2o	24.04	`2.2.5+dfsg2-8`	vulnerable
Ubuntu	h2o	24.04	`2.2.5+dfsg2-8.1ubuntu1`	vulnerable
Ubuntu	h2o	24.04	`2.2.5+dfsg2-8.1ubuntu2`	vulnerable
Ubuntu	h2o	24.04	`2.2.5+dfsg2-8.1ubuntu3`	vulnerable

Fixed-version evidence

Distribution	Package	Type	Release	Fixed version	Urgency	Origin	Bugs
Debian	h2o	source	bookworm	`Not affected`	unimportant	Not reported	Not reported

OpenFactory catalog packages

[Debian 12 (Bookworm)]

[h2o]Not affected
Details (2)
- 2.2.5+dfsg2-7 · amd64 · bookworm
  Not affected
  dsa · h2o · debian · bookworm
- 2.2.5+dfsg2-7 · arm64 · bookworm
  Not affected
  dsa · h2o · debian · bookworm
[h2o-doc]Not affected
Source package: [h2o]
Details (2)
- 2.2.5+dfsg2-7 · all · bookworm
  Not affected
  dsa · h2o · debian · bookworm
- 2.2.5+dfsg2-7 · all · bookworm
  Not affected
  dsa · h2o · debian · bookworm
[libh2o0.13]Not affected
Source package: [h2o]
Details (2)
- 2.2.5+dfsg2-7 · amd64 · bookworm
  Not affected
  dsa · h2o · debian · bookworm
- 2.2.5+dfsg2-7 · arm64 · bookworm
  Not affected
  dsa · h2o · debian · bookworm
[libh2o-dev]Not affected
Source package: [h2o]
Details (2)
- 2.2.5+dfsg2-7 · amd64 · bookworm
  Not affected
  dsa · h2o · debian · bookworm
- 2.2.5+dfsg2-7 · arm64 · bookworm
  Not affected
  dsa · h2o · debian · bookworm
[libh2o-dev-common]Not affected
Source package: [h2o]
Details (2)
- 2.2.5+dfsg2-7 · all · bookworm
  Not affected
  dsa · h2o · debian · bookworm
- 2.2.5+dfsg2-7 · all · bookworm
  Not affected
  dsa · h2o · debian · bookworm
[libh2o-evloop0.13]Not affected
Source package: [h2o]
Details (2)
- 2.2.5+dfsg2-7 · amd64 · bookworm
  Not affected
  dsa · h2o · debian · bookworm
- 2.2.5+dfsg2-7 · arm64 · bookworm
  Not affected
  dsa · h2o · debian · bookworm
[libh2o-evloop-dev]Not affected
Source package: [h2o]
Details (2)
- 2.2.5+dfsg2-7 · amd64 · bookworm
  Not affected
  dsa · h2o · debian · bookworm
- 2.2.5+dfsg2-7 · arm64 · bookworm
  Not affected
  dsa · h2o · debian · bookworm

Observed: Oct 27, 2026, 1:32:50 AM UTC

References

[Debian Security Tracker] · [FIRST EPSS] · [OSV Package Vulnerability Database]