CVE-2026-105297
7.5HighPublished 20 Oct 2026 · NVD status: Received · AI triage by gemini-3.8-flash
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
- Impact
- High impact on availability
- Weakness
- CWE-770
Impact
Remote unauthenticated attackers can crash your service via out-of-memory errors over a single HTTP/2 connection. They only need network access to any Pingora endpoint terminating HTTP/2 (h2 or h2c).
Root cause
The HTTP/2 server inherited unbounded concurrent stream limits and an oversized 16 MiB header-list limit from the h2 crate, allowing HPACK bomb requests to exhaust memory.
Affected systems
Pingora versions before 0.8.1 terminating HTTP/2 without custom stream and header limits.
CVSS v3.1 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Fix & remediation
Upgrade Pingora dependencies to 0.8.1 or later. If updating must wait or if you supply custom H2Options, explicitly configure max_header_list_size (e.g., 64 KiB) and max_concurrent_streams (e.g., 100) in your server options.
$ cargo update -p pingora --precise 0.8.1AI-suggested. Run it in staging first and check it against the vendor advisory. Why?
NVD 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.