What’s Vulnerable › Vulnerabilities

CVE-2026-97200: Unbounded response body buffering and decompression in hackney

• Severity: high (CVSS 8.2 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-26 · updated 2026-10-26
• Weakness: CWE-409

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.

Affected products

• benoitc hackney: from 2.0.0-beta.1 before 4.9.0 — fixed in 4.9.0

How to fix

Upgrade to a fixed version: benoitc hackney 4.9.0. Check the vendor advisory for mitigations.

References

• https://cna.erlef.org/cves/CVE-2026-97200.html
• https://github.com/benoitc/hackney/commit/493e8bf83a391548e5101792276ab3fc428fa76c
• https://github.com/benoitc/hackney/commit/dc41b79339ca0c41e16d3f2dd17172bc2de855d6
• https://github.com/benoitc/hackney/pull/980
• https://github.com/benoitc/hackney/releases/tag/4.9.0
• https://osv.dev/vulnerability/EEF-CVE-2026-97200

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