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


- **Severity:** High 8.2 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 26 Oct 2026
- **Updated:** 26 Oct 2026
- **Also known as:** EEF-CVE-2026-97200, GHSA-wpmp-4grc-56ph

## What is CVE-2026-97200?

CVE-2026-97200 is a high-severity vulnerability in benoitc hackney, published on 26 Oct 2026. 

### Official 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.

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling), CWE-409 (Improper Handling of Highly Compressed Data (Data Amplification))

## Which versions are affected by CVE-2026-97200?

1 open source package ship an affected version, including hackney.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `hackney` | Hex | From 2.0.0-beta.1 | 4.9.0 |

## How do I fix CVE-2026-97200?

Upgrade hackney to 4.9.0 or later.

## Is CVE-2026-97200 being exploited?

There is no known exploitation of CVE-2026-97200 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-97200 and fix it if it is affected.

What it is: CVE-2026-97200 is a high-severity vulnerability in benoitc hackney, published on 26 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-97200 in the wild and no public exploit code.

Affected packages and fixed versions:
- hackney (Hex): affected from 2.0.0-beta.1; fixed in 4.9.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-97200/ (Markdown: https://insights.sbomify.com/CVE-2026-97200/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-97200
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-97200
- OSV: https://osv.dev/vulnerability/CVE-2026-97200

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-97200/
Summaries are generated and may contain mistakes; the official description above is the record.