Inefficient Algorithmic Complexity vulnerability in elixir-mint mint allows a remote HTTP server to exhaust CPU on the client host and cause a denial of service.
\nparse_hex_prefix/2 in lib/mint/http1/parse.ex folds each hex digit of a chunked response's chunk-size field into an arbitrary-precision accumulator with acc * 16 + digit and imposes no limit on the digit count. Because the accumulator grows without bound, the multiplication is not constant time and one pass over N digits costs O(N squared). handle_data/2 prepends conn.buffer and re-parses from the start on every socket message, so a server that dribbles the digits out in small packets makes the client pay that cost repeatedly. A run of roughly 512,000 hex digits costs over ten seconds of CPU in a single pass, measured on stock defaults. The parser reaches this state after a valid status line and a complete, valid header section, so an intermediary inspecting only headers sees an ordinary 200 response.
This issue affects mint: from 1.9.3 before 1.10.0.
"},{"base64":false,"type":"text/markdown","value":"Inefficient Algorithmic Complexity vulnerability in elixir-mint mint allows a remote HTTP server to exhaust CPU on the client host and cause a denial of service.\n\n`parse_hex_prefix/2` in `lib/mint/http1/parse.ex` folds each hex digit of a chunked response's chunk-size field into an arbitrary-precision accumulator with `acc * 16 + digit` and imposes no limit on the digit count. Because the accumulator grows without bound, the multiplication is not constant time and one pass over `N` digits costs O(N squared). `handle_data/2` prepends `conn.buffer` and re-parses from the start on every socket message, so a server that dribbles the digits out in small packets makes the client pay that cost repeatedly. A run of roughly 512,000 hex digits costs over ten seconds of CPU in a single pass, measured on stock defaults. The parser reaches this state after a valid status line and a complete, valid header section, so an intermediary inspecting only headers sees an ordinary 200 response.\n\nThis issue affects mint: from 1.9.3 before 1.10.0."}],"value":"Inefficient Algorithmic Complexity vulnerability in elixir-mint mint allows a remote HTTP server to exhaust CPU on the client host and cause a denial of service.\n\nparse_hex_prefix/2 in lib/mint/http1/parse.ex folds each hex digit of a chunked response's chunk-size field into an arbitrary-precision accumulator with acc * 16 + digit and imposes no limit on the digit count. Because the accumulator grows without bound, the multiplication is not constant time and one pass over N digits costs O(N squared). handle_data/2 prepends conn.buffer and re-parses from the start on every socket message, so a server that dribbles the digits out in small packets makes the client pay that cost repeatedly. A run of roughly 512,000 hex digits costs over ten seconds of CPU in a single pass, measured on stock defaults. The parser reaches this state after a valid status line and a complete, valid header section, so an intermediary inspecting only headers sees an ordinary 200 response.\n\nThis issue affects mint: from 1.9.3 before 1.10.0."}],"impacts":[{"capecId":"CAPEC-130","descriptions":[{"lang":"en","value":"CAPEC-130 Excessive Allocation"}]}],"metrics":[{"cvssV4_0":{"Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","Safety":"NOT_DEFINED","attackComplexity":"LOW","attackRequirements":"PRESENT","attackVector":"NETWORK","baseScore":6.3,"baseSeverity":"MEDIUM","privilegesRequired":"NONE","providerUrgency":"NOT_DEFINED","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","valueDensity":"NOT_DEFINED","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","vulnerabilityResponseEffort":"NOT_DEFINED"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-407","description":"CWE-407 Inefficient Algorithmic Complexity","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-09-04T14:31:20.562Z","orgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","shortName":"EEF"},"references":[{"tags":["related","vendor-advisory"],"url":"https://github.com/elixir-mint/mint/security/advisories/GHSA-7p8w-j234-7qc8"},{"tags":["related"],"url":"https://cna.erlef.org/cves/CVE-2026-82729.html"},{"tags":["related"],"url":"https://osv.dev/vulnerability/EEF-CVE-2026-82729"},{"tags":["patch"],"url":"https://github.com/elixir-mint/mint/commit/bd2a4e7513594997c140cfef9fe0e968712fb588"}],"source":{"discovery":"EXTERNAL"},"title":"Quadratic chunk-size parsing in Mint.HTTP1.Parse allows CPU-exhaustion DoS"}},"cveMetadata":{"assignerOrgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","assignerShortName":"EEF","cveId":"CVE-2026-82729","datePublished":"2026-09-04T14:31:20.562Z","dateReserved":"2026-08-31T00:59:08.960Z","dateUpdated":"2026-09-04T14:31:20.562Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"}