https://github.com/elixir-mint/hpax/security/advisories/GHSA-jj2p-32j7-whj2

{"timestamp":"2026-07-06T12:49:38.954923Z","id":"CVE-2026-58226","options":[{"exploitation":"poc"},{"automatable":"yes"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}

Inefficient Algorithmic Complexity vulnerability in elixir-mint hpax allows unauthenticated denial-of-service via unbounded HPACK integer decoding.

hpax 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 <<< 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.

This issue affects hpax from 0.1.1 before 1.0.4.

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

CWE-407

https://cna.erlef.org/cves/CVE-2026-58226.html

https://github.com/elixir-mint/hpax/commit/1ba4bb2dc91e80089cf89c73970ac3ded76f17eb

https://github.com/elixir-mint/hpax/security/advisories/GHSA-jj2p-32j7-whj2

https://osv.dev/vulnerability/EEF-CVE-2026-58226

[{"vendor":"elixir-mint","product":"hpax","defaultStatus":"unaffected","collectionURL":"https://repo.hex.pm","packageName":"hpax","cpes":["cpe:2.3:a:elixir-mint:hpax:*:*:*:*:*:*:*:*"],"modules":["Elixir.HPAX","Elixir.HPAX.Types"],"programFiles":["lib/hpax.ex","lib/hpax/types.ex"],"programRoutines":[{"name":"'Elixir.HPAX':decode/2"},{"name":"'Elixir.HPAX.Types':decode_integer/2"},{"name":"'Elixir.HPAX.Types':decode_remaining_integer/3"}],"repo":"https://github.com/elixir-mint/hpax","packageURL":"pkg:hex/hpax","versions":[{"version":"0.1.1","lessThan":"1.0.4","versionType":"semver","status":"affected"}]},{"vendor":"elixir-mint","product":"hpax","defaultStatus":"unaffected","collectionURL":"https://github.com","packageName":"elixir-mint/hpax","cpes":["cpe:2.3:a:elixir-mint:hpax:*:*:*:*:*:*:*:*"],"modules":["Elixir.HPAX","Elixir.HPAX.Types"],"programFiles":["lib/hpax.ex","lib/hpax/types.ex"],"programRoutines":[{"name":"'Elixir.HPAX':decode/2"},{"name":"'Elixir.HPAX.Types':decode_integer/2"},{"name":"'Elixir.HPAX.Types':decode_remaining_integer/3"}],"repo":"https://github.com/elixir-mint/hpax","packageURL":"pkg:github/elixir-mint/hpax","versions":[{"version":"56db437a7e2c515e3bdd770ac7947b02cd2390d0","lessThan":"1ba4bb2dc91e80089cf89c73970ac3ded76f17eb","versionType":"git","status":"affected"}]}]