Unbounded response body buffering and decompression in hackney
At a glance
Severity
HIGH 8.2
EPSS
EPSS 0.56 % · percentile 47 (2026-10-28)
State
PUBLISHED
Published
Updated
Assigner
EEF
NVD status
Awaiting Analysis
Description
Allocation of Resources Without Limits or Throttling vulnerability in hackney_conn in benoitc hackney allows a malicious HTTP server to exhaust client memory via an oversized or highly compressed response body. hackney:request/5 and hackney:body/1 return the whole response body, and nothing bounds how much the connection process buffers. Any server the client requests can trigger it.
hackney_conn:read_full_body/2 and the HTTP/2 and HTTP/3 accumulators append every chunk until the body ends. With {auto_decompress, true} the buffered body is then inflated in one step with zlib:gunzip/1 or zlib:inflate/2, which return the whole output at once.
This issue affects hackney: from 2.0.0-beta.1 before 4.9.0.
