{"id":"CVE-2026-59246","state":"PUBLISHED","title":"Zero-length HTTP/2 CONTINUATION frames bypass Mint's header-block byte-size cap and exhaust client memory","description":"Allocation of resources without limits vulnerability in elixir-mint mint allows a remote HTTP/2 server to exhaust memory on the client host and cause a denial of service.\n\nThe Mint.HTTP2.handle_continuation/3 function in lib/mint/http2.ex accumulates the header-block fragment carried by each HTTP/2 CONTINUATION frame into a growing conn.headers_being_processed nesting, one level deeper per frame, and only releases it when a frame with the END_HEADERS flag arrives. The only guard on this accumulator is Mint.HTTP2.assert_header_block_within_max_size/2, which sums the byte size of the fragments received so far. Because a CONTINUATION frame is permitted by the protocol to carry a zero-length payload, an unbounded chain of zero-length CONTINUATION frames adds no bytes to the running total, never trips the size cap, and never emits END_HEADERS, yet each frame still nests the accumulator one level deeper.\n\nA malicious HTTP/2 server (reachable directly, via an attacker-controlled redirect, via SSRF, or via a man-in-the-middle) can open a stream by sending a HEADERS frame without END_HEADERS and then stream zero-length CONTINUATION frames indefinitely. Client memory grows one cons cell per frame received; sustained bandwidth from the peer drives the BEAM node running the Mint client to memory exhaustion and eventual out-of-memory termination.\n\nThis issue affects mint: from 0.1.0 before 1.9.2.","publishedAt":"2026-07-14T08:37:04.609Z","updatedAt":"2026-07-14T15:08:39.463Z","severity":{"score":6.3,"label":"Medium","version":"4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","source":"EEF"},"assigner":"EEF","products":["elixir-mint mint"],"affected":[{"vendor":"elixir-mint","product":"mint","packageName":"mint","packageURL":"pkg:hex/mint","defaultStatus":"unaffected","versions":[{"version":"0.1.0","status":"affected","lessThan":"1.9.2","versionType":"semver"}],"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:elixir-mint:mint:*:*:*:*:*:*:*:*"],"modules":["'Elixir.Mint.HTTP2'"],"programFiles":["lib/mint/http2.ex"],"programRoutines":[{"name":"'Elixir.Mint.HTTP2':handle_continuation/3"},{"name":"'Elixir.Mint.HTTP2':assert_header_block_within_max_size/2"}],"repo":"https://github.com/elixir-mint/mint"},{"vendor":"elixir-mint","product":"mint","packageName":"elixir-mint/mint","packageURL":"pkg:github/elixir-mint/mint","defaultStatus":"unaffected","versions":[{"version":"596ca4304504be68939c4929e0831557097962b8","status":"affected","lessThan":"5779de1666344b32aefc4354184ea07f902f73ce","versionType":"git"}],"collectionURL":"https://github.com","cpes":["cpe:2.3:a:elixir-mint:mint:*:*:*:*:*:*:*:*"],"modules":["'Elixir.Mint.HTTP2'"],"programFiles":["lib/mint/http2.ex"],"programRoutines":[{"name":"'Elixir.Mint.HTTP2':handle_continuation/3"},{"name":"'Elixir.Mint.HTTP2':assert_header_block_within_max_size/2"}],"repo":"https://github.com/elixir-mint/mint"}],"references":["https://github.com/elixir-mint/mint/security/advisories/GHSA-8pf6-g464-h6h9","https://cna.erlef.org/cves/CVE-2026-59246.html","https://osv.dev/vulnerability/EEF-CVE-2026-59246","https://github.com/elixir-mint/mint/commit/5779de1666344b32aefc4354184ea07f902f73ce"],"weaknesses":["CWE-770"],"ingestedAt":"2026-10-29T20:12:32.778Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/59xxx/CVE-2026-59246.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-59246","state":"PUBLISHED","datePublished":"2026-07-14T08:37:04.609Z","dateUpdated":"2026-07-14T15:08:39.463Z","assignerShortName":"EEF","assignerOrgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","dateReserved":"2026-07-04T04:24:03.652Z"},"containers":{"cna":{"title":"Zero-length HTTP/2 CONTINUATION frames bypass Mint's header-block byte-size cap and exhaust client memory","descriptions":[{"lang":"en","value":"Allocation of resources without limits vulnerability in elixir-mint mint allows a remote HTTP/2 server to exhaust memory on the client host and cause a denial of service.\n\nThe Mint.HTTP2.handle_continuation/3 function in lib/mint/http2.ex accumulates the header-block fragment carried by each HTTP/2 CONTINUATION frame into a growing conn.headers_being_processed nesting, one level deeper per frame, and only releases it when a frame with the END_HEADERS flag arrives. The only guard on this accumulator is Mint.HTTP2.assert_header_block_within_max_size/2, which sums the byte size of the fragments received so far. Because a CONTINUATION frame is permitted by the protocol to carry a zero-length payload, an unbounded chain of zero-length CONTINUATION frames adds no bytes to the running total, never trips the size cap, and never emits END_HEADERS, yet each frame still nests the accumulator one level deeper.\n\nA malicious HTTP/2 server (reachable directly, via an attacker-controlled redirect, via SSRF, or via a man-in-the-middle) can open a stream by sending a HEADERS frame without END_HEADERS and then stream zero-length CONTINUATION frames indefinitely. Client memory grows one cons cell per frame received; sustained bandwidth from the peer drives the BEAM node running the Mint client to memory exhaustion and eventual out-of-memory termination.\n\nThis issue affects mint: from 0.1.0 before 1.9.2."}],"affected":[{"vendor":"elixir-mint","product":"mint","packageName":"mint","packageURL":"pkg:hex/mint","defaultStatus":"unaffected","versions":[{"version":"0.1.0","status":"affected","lessThan":"1.9.2","versionType":"semver"}],"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:elixir-mint:mint:*:*:*:*:*:*:*:*"],"modules":["'Elixir.Mint.HTTP2'"],"programFiles":["lib/mint/http2.ex"],"programRoutines":[{"name":"'Elixir.Mint.HTTP2':handle_continuation/3"},{"name":"'Elixir.Mint.HTTP2':assert_header_block_within_max_size/2"}],"repo":"https://github.com/elixir-mint/mint"},{"vendor":"elixir-mint","product":"mint","packageName":"elixir-mint/mint","packageURL":"pkg:github/elixir-mint/mint","defaultStatus":"unaffected","versions":[{"version":"596ca4304504be68939c4929e0831557097962b8","status":"affected","lessThan":"5779de1666344b32aefc4354184ea07f902f73ce","versionType":"git"}],"collectionURL":"https://github.com","cpes":["cpe:2.3:a:elixir-mint:mint:*:*:*:*:*:*:*:*"],"modules":["'Elixir.Mint.HTTP2'"],"programFiles":["lib/mint/http2.ex"],"programRoutines":[{"name":"'Elixir.Mint.HTTP2':handle_continuation/3"},{"name":"'Elixir.Mint.HTTP2':assert_header_block_within_max_size/2"}],"repo":"https://github.com/elixir-mint/mint"}],"references":[{"url":"https://github.com/elixir-mint/mint/security/advisories/GHSA-8pf6-g464-h6h9","tags":["vendor-advisory","related"]},{"url":"https://cna.erlef.org/cves/CVE-2026-59246.html","tags":["related"]},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-59246","tags":["related"]},{"url":"https://github.com/elixir-mint/mint/commit/5779de1666344b32aefc4354184ea07f902f73ce","tags":["patch"]}],"metrics":[{"cvssV4_0":{"attackComplexity":"LOW","attackRequirements":"PRESENT","attackVector":"NETWORK","baseScore":6.3,"baseSeverity":"MEDIUM","privilegesRequired":"NONE","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","vectorString":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","version":"4.0","vulnAvailabilityImpact":"LOW","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-770","description":"CWE-770 Allocation of Resources Without Limits or Throttling","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"EEF","orgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","dateUpdated":"2026-07-14T15:08:39.463Z"},"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:a:elixir-mint:mint:*:*:*:*:*:*:*:*","versionEndExcluding":"1.9.2","versionStartIncluding":"0.1.0","vulnerable":true}],"negate":false,"operator":"OR"}],"operator":"AND"}],"credits":[{"lang":"en","type":"finder","value":"zx (Jace)"},{"lang":"en","type":"remediation developer","value":"Andrea Leopardi"},{"lang":"en","type":"remediation reviewer","value":"Eric Meadows-Jönsson"},{"lang":"en","type":"analyst","value":"Jonatan Männchen / EEF"}],"impacts":[{"capecId":"CAPEC-130","descriptions":[{"lang":"en","value":"CAPEC-130 Excessive Allocation"}]}],"source":{"discovery":"EXTERNAL"},"x_generator":{"engine":"cvelib 1.8.0"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/elixir-mint/mint/security/advisories/GHSA-8pf6-g464-h6h9","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-07-14T12:25:59.949476Z","id":"CVE-2026-59246","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-07-14T12:26:05.211Z"}}]}}}