{"id":"CVE-2026-105297","state":"PUBLISHED","title":"Pingora HTTP/2 server memory exhaustion through unbounded default header-list and concurrent-stream limits","description":"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.","publishedAt":"2026-10-20T00:40:27.300Z","updatedAt":"2026-10-20T19:20:35.542Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"cloudflare"},"assigner":"cloudflare","products":["Cloudflare https://github.com/cloudflare/pingora"],"affected":[{"vendor":"Cloudflare","product":"https://github.com/cloudflare/pingora","defaultStatus":"unaffected","versions":[{"version":"0.1.0","status":"affected","lessThan":"0.8.1","versionType":"semver"}],"repo":"https://github.com/cloudflare/pingora"}],"references":["https://github.com/cloudflare/pingora"],"weaknesses":["CWE-770"],"ingestedAt":"2026-10-29T20:10:23.711Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/105xxx/CVE-2026-105297.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-105297","state":"PUBLISHED","datePublished":"2026-10-20T00:40:27.300Z","dateUpdated":"2026-10-20T19:20:35.542Z","assignerShortName":"cloudflare","assignerOrgId":"a22f1246-ba21-4bb4-a601-ad51614c1513","dateReserved":"2026-10-05T04:18:56.102Z"},"containers":{"cna":{"title":"Pingora HTTP/2 server memory exhaustion through unbounded default header-list and concurrent-stream limits","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"Cloudflare","product":"https://github.com/cloudflare/pingora","defaultStatus":"unaffected","versions":[{"version":"0.1.0","status":"affected","lessThan":"0.8.1","versionType":"semver"}],"repo":"https://github.com/cloudflare/pingora"}],"references":[{"url":"https://github.com/cloudflare/pingora"}],"metrics":[{"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}],"cvssV3_1":{"version":"3.1","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH","baseSeverity":"HIGH","baseScore":7.5,"vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-770","lang":"en","description":"CWE-770 Allocation of resources without limits or throttling","type":"CWE"}]}],"providerMetadata":{"shortName":"cloudflare","orgId":"a22f1246-ba21-4bb4-a601-ad51614c1513","dateUpdated":"2026-10-20T00:40:27.300Z"},"solutions":[{"lang":"en","value":"Mitigation:\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.","supportingMedia":[{"type":"text/html","base64":false,"value":"<b><p>Mitigation:</p><ul><li><p>Upgrade to pingora 0.8.1 or later (fix: <a href=\"https://github.com/cloudflare/pingora/commit/d193c8d49b8b7c1c1ede93183759caa4f6906bbd\">https://github.com/cloudflare/pingora/commit/d193c8d49b8b7c1c1ede93183759caa4f6906bbd</a>). 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.</p></li><li><p>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.</p></li></ul></b>"}]}],"credits":[{"lang":"en","value":"Reported by jro-calif (GitHub)","type":"reporter"}],"source":{"discovery":"UNKNOWN"},"x_generator":{"engine":"Vulnogram 1.0.5"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-10-20T19:20:25.097096Z","id":"CVE-2026-105297","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-20T19:20:35.542Z"}}]}}}