CVE-2026-105297 Pingora HTTP/2 server memory exhaustion through unbounded default header-list and concurrent-stream limits

What is CVE-2026-105297?

CVE-2026-105297 is a high-severity vulnerability in https://github.com/cloudflare/pingora, published on 20 Oct 2026.

Official 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.

Weakness: CWE-770

Which versions are affected by CVE-2026-105297?

1 open source package ship an affected version, including pingora-core.

How do I fix CVE-2026-105297?

Upgrade pingora-core to 0.8.1 or later.

Is CVE-2026-105297 being exploited?

There is no known exploitation of CVE-2026-105297 in the wild and no public exploit code.

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• GitHub advisory
• How this page is made

Also known as GHSA-7gpj-mj4q-x62x, GHSA-x6pg-x323-jhc4, RUSTSEC-2026-0389.