CVE-2026-55213

CVE-2026-55213 (h2o HTTP server) – Affected component: lib/http3/qpack.c, invoked while processing a QPACK instruction over HTTP/3. Root cause: on-stack allocation of a large buffer (up to ~800 KB) via alloca, exceeding default musl libc pthread stack size, leading to a segmentation fault when to...

CVE-2026-55213 h2o: musl libc stack overflow (QPACK)

h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. Prior to commit edd7a120bfc4af11ac0cbebce2a43cc1f93f9af1, when h2o processes a QPACK instruction sent from the peer over HTTP/3, lib/http3/qpack.c might allocate an on-stack buffer as large as approximately 800 KB by calling...

CVE-2023-50247

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 progressivel...

EUVD-2024-41461

Malicious code in bioql PyPI...

EUVD-2023-55065

Malicious code in bioql PyPI...

Linux Distros Unpatched Vulnerability : CVE-2021-43848

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - h2o is an open source http server. In code prior to the 8c0eca3 commit h2o may attempt to access uninitialized memory. When receiving QUIC frames in certain...

Linux Distros Unpatched Vulnerability : CVE-2024-45403

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - 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, h...

Linux Distros Unpatched Vulnerability : CVE-2024-45397

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. When an HTTP request using TLS/1.3 early data on top of TCP Fast Open or QUIC 0-RTT packets ...

Linux Distros Unpatched Vulnerability : CVE-2018-0608

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - Buffer overflow in H2O version 2.2.4 and earlier allows remote attackers to execute arbitrary code or cause a denial of service DoS via unspecified vectors...

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, th...

CVE-2023-41337

h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. In version 2.3.0-beta2 and prior, when h2o is configured to listen to multiple addresses or ports with each of them using different backend servers managed by multiple entities, a malicious backend entity that also has the...

CVE-2023-30847

H2O is an HTTP server. In versions 2.3.0-beta2 and prior, when the reverse proxy handler tries to processes a certain type of invalid HTTP request, it tries to build an upstream URL by reading from uninitialized pointer. This behavior can lead to crashes or leak of information to back end HTTP...

DEBIAN-CVE-2024-45397

h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. When an HTTP request using TLS/1.3 early data on top of TCP Fast Open or QUIC 0-RTT packets is received and the IP-address-based access control is used, the access control does not detect and prohibit HTTP requests conveyed by...

CVE-2024-45397

h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. When an HTTP request using TLS/1.3 early data on top of TCP Fast Open or QUIC 0-RTT packets is received and the IP-address-based access control is used, the access control does not detect and prohibit HTTP requests conveyed by...

UBUNTU-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, th...

CVE-2024-45403 H2O assertion failure when HTTP/3 requests are cancelled

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, th...

CVE-2024-45397 H2O alllows bypassing address-based access control with 0-RTT

h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. When an HTTP request using TLS/1.3 early data on top of TCP Fast Open or QUIC 0-RTT packets is received and the IP-address-based access control is used, the access control does not detect and prohibit HTTP requests conveyed by...

CVE-2024-25622 H2O ignores headers configuration directives

h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. The configuration directives provided by the headers handler allows users to modify the response headers being sent by h2o. The configuration file of h2o has scopes, and the inner scopes e.g., path level are expected to inherit t...

CVE-2024-25622 H2O ignores headers configuration directives

h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. The configuration directives provided by the headers handler allows users to modify the response headers being sent by h2o. The configuration file of h2o has scopes, and the inner scopes e.g., path level are expected to inherit t...

PT-2024-31607 · H2O · H2O

Name of the Vulnerable Software and Affected Versions: h2o versions prior to the version containing commit 1ed32b2 Description: The issue affects h2o, an HTTP server that supports HTTP/1.x, HTTP/2, and HTTP/3. When configured as a reverse proxy, h2o may crash due to an assertion failure if HTTP/3...