CVE-2026-105297
HighCVSS 7.5Summary
Before version 0.8.1, Pingora's HTTP/2 server used the h2 crate's default limits, allowing a remote, unauthenticated client to send 1-byte HPACK references to a near-empty header. This caused the server to allocate hundreds of thousands of header fields per stream across an unlimited number of streams on one connection, potentially exhausting memory and terminating the Pingora process.
Risk Assessment
A remote, unauthenticated attacker can cause a denial of service (OOM) against Pingora services terminating HTTP/2 (h2 or h2c) without explicitly set max_header_list_size and max_concurrent_streams. A single connection could get a Pingora process with a 2 GiB memory limit OOM-killed.
Recommendation
Upgrade to Pingora 0.8.1 or later, which enforces a 64 KiB decoded header-list limit and at most 100 concurrent streams per connection by default. Applications supplying their own H2Options must explicitly set max_header_list_size and max_concurrent_streams or use default_h2_options() on 0.8.1+.
Other vulnerabilities in Pingora
See all- CVE-2026-105299High
Before version 0.9.0, the HTTP/1 upstream path in pingora-proxy did not remove the Connection header, other hop-by-hop headers, or headers nominated by Connection, despite RFC 9110 requirements. A client could nominate a header added by the application in upstream_request_filter (e.g., X-Forwarded-For), which would then be stripped by an HTTP/1 intermediary before reaching the origin.
- CVE-2026-105298Medium
Before version 0.9.0, Pingora accepted HTTP/2 requests where the Host header differed from the :authority pseudo-header. Request filters, cache keys, and logs saw the :authority value, but the upstream received the client-supplied Host value. Pingora also accepted :authority values containing userinfo (e.g., [email protected]), violating RFC 9113 Section 8.3.1.
Original NVD description (English source)
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.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS