CVE-2026-54340

CVE-2026-54340 affects the h2o HTTP server (HTTP/2) and describes an HTTP/2 state amplification issue where HPACK decompression amplification combines with Slowloris-style stream stalling. Amplified decoded header state can be retained by stalled HTTP/2 streams; depending on configuration, additi...

CVE-2026-55204

A flaw was found in HAProxy. An attacker can trigger HPACK dynamic table insertions under memory pressure, leading to a null pointer dereference in the hpackdhtinsert function. This can cause HAProxy worker processes to crash, resulting in a denial of service DoS. Mitigation Mitigation for this...

PT-2026-60605

h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. Prior to commit 9265bdd, there is an HTTP/2 state amplification issue that combines HPACK decompression amplification with Slowloris-style stream stalling. Amplified decoded header state can be retained by stalled HTTP/2 streams,...

CVE-2026-12523 Resource exhaustion in quiche HTTP/3 and QPACK layers

Summary Cloudflare quiche's HTTP/3 layer was discovered to be vulnerable to resource exhaustion i.e., memory by means of specially crafted HTTP/3 frames. Impact HTTP/3 defines multiple frame types to support HTTP message exchanges and connection management. Each frame has a length and a payload...

CVE-2026-54428

A flaw was found in Apache HttpComponents Core. This vulnerability, located in the HTTP/2 HPACK decoder, allows a remote attacker to cause a denial of service. By sending oversized compressed header blocks, an attacker can exhaust memory resources before the system's configured header list size...

Unpatched XRING Flaw in XQUIC Lets Remote Clients Crash HTTP/3 Servers

A single wrong variable on one line in XQUIC, Alibaba's QUIC and HTTP/3 library, lets any remote client crash the server with a short burst of completely legal traffic. There is no patch. FoxIO researcher Sébastien Féry disclosed the flaw on July 8 and nicknamed it XRING. He says it needs no logi...

httpd: httpd: HTTP/2 Remote Denial of Service via compression bomb and Slowloris-style attack

A flaw was found in HTTP/2, affecting various web servers. A remote attacker can exploit this vulnerability by combining an HPACK compression bomb with a zero-byte flow-control window. This technique allows a small amount of data to expand into large memory allocations on the server, which are th...

Apache HttpComponents Core resource management error vulnerability

Apache HttpComponents Core is an open-source core library for HTTP components developed by the Apache Foundation in the United States. There is a resource management vulnerability in Apache HttpComponents Core. This vulnerability stems from unlimited or throttled resource allocation in the HTTP/2...

httpd: httpd: HTTP/2 Remote Denial of Service via compression bomb and Slowloris-style attack

A flaw was found in HTTP/2, affecting various web servers. A remote attacker can exploit this vulnerability by combining an HPACK compression bomb with a zero-byte flow-control window. This technique allows a small amount of data to expand into large memory allocations on the server, which are th...

GO-2026-5676 HTTP/3 QPACK Trailer Expansion Memory Exhaustion in github.com/quic-go/quic-go

HTTP/3 QPACK Trailer Expansion Memory Exhaustion in github.com/quic-go/quic-go...

Excessive Iteration in gRPC

gRPC contains a vulnerability that allows hpack table accounting errors could lead to unwanted disconnects between clients and servers in exceptional cases/Three vectors were found that allow the following DOS attacks:- Unbounded memory buffering in the HPACK parser- Unbounded CPU consumption in...

PYSEC-2026-1424 Excessive Iteration in gRPC

gRPC contains a vulnerability that allows hpack table accounting errors could lead to unwanted disconnects between clients and servers in exceptional cases/ Three vectors were found that allow the following DOS attacks: - Unbounded memory buffering in the HPACK parser - Unbounded CPU consumption ...

EEF-CVE-2026-58226 Unauthenticated denial-of-service via unbounded HPACK integer decoding in hpax

Summary Inefficient Algorithmic Complexity vulnerability in elixir-mint hpax allows unauthenticated denial-of-service via unbounded HPACK integer decoding. hpax decodes HPACK variable-length integers with no upper bound on the decoded value or the number of continuation octets...

CVE-2026-58226

CVE-2026-58226 affects the hpax component of elixir-mint. The vulnerability is in Elixir.HPAX.Types:decode_remaining_integer/3 , which decodes HPACK integers without an upper bound, allowing an unauthenticated attacker to trigger excessive CPU and transient memory via a small HTTP/2 header block....

haproxy: HAProxy: Denial of Service via HPACK dynamic table insertions

A flaw was found in HAProxy. An attacker can trigger HPACK dynamic table insertions under memory pressure, leading to a null pointer dereference in the hpackdhtinsert function. This can cause HAProxy worker processes to crash, resulting in a denial of service DoS...

CVE-2026-54428

Allocation of resources without limits or throttling in the HTTP/2 HPACK decoder in Apache HttpComponents Core 5.4.2 and earlier, 5.5-beta1 and earlier allows an remote attacker to cause a denial of service through memory exhaustion by sending oversized compressed header blocks before the HTTP/2...

EUVD-2026-41095

Allocation of resources without limits or throttling in the HTTP/2 HPACK decoder in Apache HttpComponents Core 5.4.2 and earlier, 5.5-beta1 and earlier allows an remote attacker to cause a denial of service through memory exhaustion by sending oversized compressed header blocks before the HTTP/2...

CVE-2026-54428

The CVE concerns Apache HttpComponents Core HPACK decoder: on HTTP/2, the HPACK decoder may allocate resources without limits or throttling, allowing a remote attacker to cause memory exhaustion and denial of service. Affected versions are 5.4.2 and earlier, and 5.5-beta1 and earlier. The issue o...

JLSEC-2026-624 HTTP/2 client HPACK desynchronization via header blocks for unknown streams in HTTP.jl

Description The HTTP/2 client's processincomingframe! dropped HEADERS/CONTINUATION frames for stream ids absent from conn.streams without passing the header block through the connection's HPACK decoder. Because HPACK's dynamic table is connection-scoped and mutated as a side effect of decoding ea...

httpd: httpd: HTTP/2 Remote Denial of Service via compression bomb and Slowloris-style attack

A flaw was found in HTTP/2, affecting various web servers. A remote attacker can exploit this vulnerability by combining an HPACK compression bomb with a zero-byte flow-control window. This technique allows a small amount of data to expand into large memory allocations on the server, which are th...