CVE-2026-105297
Received Received - Intake

Denial of Service in Pingora HTTP/2 Server

Publication date: 2026-10-20

Last updated on: 2026-10-20

Assigner: Cloudflare, Inc.

Description
Summary Before version 0.8.1, Pingora's HTTP/2 server used the h2 crate's default limits unless the application set its own 16 MiB decoded header-list size and no limit on concurrent streams. A remote, unauthenticated client can send 1-byte HPACK references to a near-empty header, making the server allocate hundreds of thousands of header fields per stream across an unlimited number of streams on one connection, and use HTTP/2 flow control to keep those streams open. This can exhaust memory and degrade or terminate the Pingora process. Impact Remote, unauthenticated denial of service against any Pingora service that terminates HTTP/2 (h2 or h2c) without explicitly setting max_header_list_size and max_concurrent_streams. The reporter showed that a single connection could get a Pingora process with a 2 GiB memory limit OOM-killed. Note that Cloudflare CDN customers were unaffected, as internal Pingora services at Cloudflare do not have HTTP/2 clients. Mitigation: * Upgrade to pingora 0.8.1 or later (fix: https://github.com/cloudflare/pingora/commit/d193c8d49b8b7c1c1ede93183759caa4f6906bbd ). When no H2Options are supplied, Pingora now advertises and enforces a 64 KiB decoded header-list limit and at most 100 concurrent streams per connection. * Applications that supply their own H2Options are not covered by these defaults and must set max_header_list_size and max_concurrent_streams explicitly (this also works on versions before 0.8.1), or, on 0.8.1 and later, start from pingora_core::protocols::http::v2::server::default_h2_options(). H2Options::default() does not include these limits.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published
2026-10-20
Last Modified
2026-10-20
Generated
2026-10-20
AI Q&A
2026-10-20
EPSS Evaluated
N/A
NVD
CVE-2026-105297
EUVD
EUVD-2026-104678

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
Cloudflare https://github.com/cloudflare/pingora 0.1.0

Helpful Resources

Exploitability

CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-770 The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.

Attack-Flow Graph

AI Quick Actions

Instant insights powered by AI
Executive Summary

This is a denial of service vulnerability in Pingora's HTTP/2 server before version 0.8.1. A remote attacker can send specially crafted requests to exhaust server memory by forcing it to allocate excessive header fields across many streams. The server uses default limits that allow this attack unless custom limits are set.

Impact Analysis

If you run a service using Pingora's HTTP/2 server before 0.8.1 without custom limits, an attacker could crash your service by consuming all available memory. This would make your service unavailable to legitimate users.

Mitigation Strategies

Upgrade to Pingora version 0.8.1 or later to enforce default limits of 64 KiB header size and 100 concurrent streams. If using custom H2Options, explicitly set max_header_list_size and max_concurrent_streams or use default_h2_options().

Chat Assistant

Ask questions about this CVE
Hi! I’m here to help you understand CVE-2026-105297. Ask me anything about the vulnerability, its impact, or mitigation strategies.
0/70

EPSS Chart