{"id":"CVE-2026-105297","summary":"Pingora HTTP/2 server memory exhaustion through unbounded default header-list and concurrent-stream limits","details":"Summary\n\n\n\nBefore 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.\n\n\n\n\nImpact\n\n\n\nRemote, 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.\n\n\n\n\nNote that Cloudflare CDN customers were unaffected, as internal Pingora services at Cloudflare do not have HTTP/2 clients.\n\n\n\nMitigation:\n\n  *  \n\nUpgrade 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.\n\n\n  *  \n\nApplications 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.","modified":"2026-10-20T11:15:59.073853428Z","published":"2026-10-20T00:40:27.300Z","database_specific":{"cna_assigner":"cloudflare","cwe_ids":["CWE-770"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/105xxx/CVE-2026-105297.json"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/105xxx/CVE-2026-105297.json"},{"type":"PACKAGE","url":"https://github.com/cloudflare/pingora"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-105297"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/cloudflare/pingora","events":[{"introduced":"b4264f1f2499762b8fe33e75d9f4ee1dc2db2fdb"},{"fixed":"719ef6cd54e40b530127751bab6c1afc5ae815a8"}],"database_specific":{"extracted_events":[{"introduced":"0.1.0"},{"fixed":"0.8.1"}],"source":"AFFECTED_FIELD"}}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-105297.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}