{"id":"CVE-2026-58226","aliases":["EEF-CVE-2026-58226","EUVD-2026-41861","GHSA-jj2p-32j7-whj2"],"status":"published","title":"Unauthenticated denial-of-service via unbounded HPACK integer decoding in hpax","description":"Inefficient Algorithmic Complexity vulnerability in elixir-mint hpax allows unauthenticated denial-of-service via unbounded HPACK integer decoding.\n\nhpax decodes HPACK variable-length integers with no upper bound on the decoded value or the number of continuation octets. 'Elixir.HPAX.Types':decode_remaining_integer/3 accumulates the integer as int + (value \u003c\u003c\u003c m), shifting by 7 more bits for each continuation octet and stopping only on a terminating octet or truncated input, never because the integer grew too large. Because BEAM integers are arbitrary precision, a run of N continuation octets builds an O(N)-bit bignum and re-adds into an ever-larger bignum on each step, so the total decoding cost is superlinear (about O(N^2)). An unauthenticated attacker who can send an HTTP/2 header block to a server using this decoder (reached through the 'Elixir.HPAX':decode/2 entry point) can supply a small header block that forces a large, attacker-controlled amount of CPU (and transient memory), a denial-of-service amplification.\n\nThis issue affects hpax from 0.1.1 before 1.0.4.","severity":{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00574,"percentile":0.47847,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-407"],"published":"2026-07-06T09:03:47Z","modified":"2026-10-28T02:31:00Z","fixes":[{"ecosystem":"Hex","package":"hpax","fixed_in":["1.0.4"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Hex","package":"hpax","ranges":[{"type":"SEMVER","events":[{"introduced":"0.1.1"},{"fixed":"1.0.4"}]}],"versions":["0.1.1","0.1.2","0.2.0","1.0.0","1.0.1","1.0.2","1.0.3"]}],"products":[{"vendor":"elixir-mint","product":"hpax"}],"references":[{"url":"https://github.com/elixir-mint/hpax/security/advisories/GHSA-jj2p-32j7-whj2","tags":["vendor-advisory","related","exploit","advisory"]},{"url":"https://cna.erlef.org/cves/CVE-2026-58226.html","tags":["related","web"]},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-58226","tags":["related","web"]},{"url":"https://github.com/elixir-mint/hpax/commit/1ba4bb2dc91e80089cf89c73970ac3ded76f17eb","tags":["patch","fix"]},{"url":"https://github.com","tags":["web"]},{"url":"https://repo.hex.pm","tags":["web"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/58xxx/CVE-2026-58226.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-58226","tags":["advisory"]},{"url":"https://github.com/elixir-mint/hpax","tags":["package"]},{"url":"https://hex.pm/packages/hpax","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-58226","title":"Unauthenticated denial-of-service via unbounded HPACK integer decoding in hpax","description":"Inefficient Algorithmic Complexity vulnerability in elixir-mint hpax allows unauthenticated denial-of-service via unbounded HPACK integer decoding.\n\nhpax decodes HPACK variable-length integers with no upper bound on the decoded value or the number of continuation octets. 'Elixir.HPAX.Types':decode_remaining_integer/3 accumulates the integer as int + (value \u003c\u003c\u003c m), shifting by 7 more bits for each continuation octet and stopping only on a terminating octet or truncated input, never because the integer grew too large. Because BEAM integers are arbitrary precision, a run of N continuation octets builds an O(N)-bit bignum and re-adds into an ever-larger bignum on each step, so the total decoding cost is superlinear (about O(N^2)). An unauthenticated attacker who can send an HTTP/2 header block to a server using this decoder (reached through the 'Elixir.HPAX':decode/2 entry point) can supply a small header block that forces a large, attacker-controlled amount of CPU (and transient memory), a denial-of-service amplification.\n\nThis issue affects hpax from 0.1.1 before 1.0.4.","status":"published","published":"2026-07-06T09:03:47.374Z","modified":"2026-07-06T14:04:14.632Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high","assessor":"cna"}],"cwes":["CWE-407"],"updated_at":"2026-11-02T13:47:28.691429Z"}],"euvd":[{"id":"EUVD-2026-41861","description":"Inefficient Algorithmic Complexity vulnerability in elixir-mint hpax allows unauthenticated denial-of-service via unbounded HPACK integer decoding.\n\nhpax decodes HPACK variable-length integers with no upper bound on the decoded value or the number of continuation octets. 'Elixir.HPAX.Types':decode_remaining_integer/3 accumulates the integer as int + (value \u003c\u003c\u003c m), shifting by 7 more bits for each continuation octet and stopping only on a terminating octet or truncated input, never because the integer grew too large. Because BEAM integers are arbitrary precision, a run of N continuation octets builds an O(N)-bit bignum and re-adds into an ever-larger bignum on each step, so the total decoding cost is superlinear (about O(N^2)). An unauthenticated attacker who can send an HTTP/2 header block to a server using this decoder (reached through the 'Elixir.HPAX':decode/2 entry point) can supply a small header block that forces a large, attacker-controlled amount of CPU (and transient memory), a denial-of-service amplification.\n\nThis issue affects hpax from 0.1.1 before 1.0.4.","status":"published","published":"2026-07-06T09:03:47Z","modified":"2026-07-06T14:04:14Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high"}],"updated_at":"2026-11-02T18:20:13.541613Z"}],"nvd":[{"id":"CVE-2026-58226","description":"Inefficient Algorithmic Complexity vulnerability in elixir-mint hpax allows unauthenticated denial-of-service via unbounded HPACK integer decoding.\n\nhpax decodes HPACK variable-length integers with no upper bound on the decoded value or the number of continuation octets. 'Elixir.HPAX.Types':decode_remaining_integer/3 accumulates the integer as int + (value \u003c\u003c\u003c m), shifting by 7 more bits for each continuation octet and stopping only on a terminating octet or truncated input, never because the integer grew too large. Because BEAM integers are arbitrary precision, a run of N continuation octets builds an O(N)-bit bignum and re-adds into an ever-larger bignum on each step, so the total decoding cost is superlinear (about O(N^2)). An unauthenticated attacker who can send an HTTP/2 header block to a server using this decoder (reached through the 'Elixir.HPAX':decode/2 entry point) can supply a small header block that forces a large, attacker-controlled amount of CPU (and transient memory), a denial-of-service amplification.\n\nThis issue affects hpax from 0.1.1 before 1.0.4.","status":"published","published":"2026-07-06T11:16:31.143Z","modified":"2026-10-25T20:10:00.147Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high","assessor":"secondary"}],"cwes":["CWE-407"],"updated_at":"2026-11-02T14:12:28.040501Z"}],"osv":[{"id":"CVE-2026-58226","title":"Unauthenticated denial-of-service via unbounded HPACK integer decoding in hpax","description":"Inefficient Algorithmic Complexity vulnerability in elixir-mint hpax allows unauthenticated denial-of-service via unbounded HPACK integer decoding.\n\nhpax decodes HPACK variable-length integers with no upper bound on the decoded value or the number of continuation octets. 'Elixir.HPAX.Types':decode_remaining_integer/3 accumulates the integer as int + (value \u003c\u003c\u003c m), shifting by 7 more bits for each continuation octet and stopping only on a terminating octet or truncated input, never because the integer grew too large. Because BEAM integers are arbitrary precision, a run of N continuation octets builds an O(N)-bit bignum and re-adds into an ever-larger bignum on each step, so the total decoding cost is superlinear (about O(N^2)). An unauthenticated attacker who can send an HTTP/2 header block to a server using this decoder (reached through the 'Elixir.HPAX':decode/2 entry point) can supply a small header block that forces a large, attacker-controlled amount of CPU (and transient memory), a denial-of-service amplification.\n\nThis issue affects hpax from 0.1.1 before 1.0.4.","status":"published","published":"2026-07-06T09:03:47.374Z","modified":"2026-10-28T02:31:00.543902213Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-407"],"updated_at":"2026-11-02T15:45:12.016252Z"},{"id":"EEF-CVE-2026-58226","title":"Unauthenticated denial-of-service via unbounded HPACK integer decoding in hpax","description":"## Summary\n\nInefficient Algorithmic Complexity vulnerability in elixir-mint hpax allows unauthenticated denial-of-service via unbounded HPACK integer decoding.\n\nhpax decodes HPACK variable-length integers with no upper bound on the decoded value or the number of continuation octets. 'Elixir.HPAX.Types':decode\\_remaining\\_integer/3 accumulates the integer as int + (value \u003c\u003c\u003c m), shifting by 7 more bits for each continuation octet and stopping only on a terminating octet or truncated input, never because the integer grew too large. Because BEAM integers are arbitrary precision, a run of N continuation octets builds an O(N)-bit bignum and re-adds into an ever-larger bignum on each step, so the total decoding cost is superlinear (about O(N^2)). An unauthenticated attacker who can send an HTTP/2 header block to a server using this decoder (reached through the 'Elixir.HPAX':decode/2 entry point) can supply a small header block that forces a large, attacker-controlled amount of CPU (and transient memory), a denial-of-service amplification.\n\nThis issue affects hpax from 0.1.1 before 1.0.4.","status":"published","published":"2026-07-06T09:03:47.374Z","modified":"2026-07-30T18:22:03.167317Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-407"],"updated_at":"2026-11-02T15:46:33.520522Z"}]}}