---
id: CVE-2026-48594
aliases:
  - GHSA-mc85-72gr-vm9f
title: Tesla has decompression bomb on response body
summary: Tesla has decompression bomb on response body
severity: high
cwe:
  - CWE-409
vendor: tesla
product: tesla
ecosystem: erlang
affected:
  - 'tesla >= 0.6.0, < 1.18.3'
patched:
  - tesla 1.18.3
published: '2026-07-10'
updated: '2026-07-10'
source: GHSA
sourceUrl: 'https://github.com/advisories/GHSA-mc85-72gr-vm9f'
references:
  - url: >-
      https://github.com/elixir-tesla/tesla/security/advisories/GHSA-mc85-72gr-vm9f
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-48594'
  - url: >-
      https://github.com/elixir-tesla/tesla/commit/340f75b5d191dc747ef7ac6365bd002d1cd55a9d
  - url: 'https://cna.erlef.org/cves/CVE-2026-48594.html'
  - url: 'https://osv.dev/vulnerability/EEF-CVE-2026-48594'
  - url: 'https://github.com/advisories/GHSA-mc85-72gr-vm9f'
tags:
  - ghsa
  - erlang
epss: 0.00455
epssPercentile: 0.38713
ingestedAt: '2026-07-10T00:54:12.242Z'
---

## Overview

### Summary

Any Tesla client pipeline that includes `Tesla.Middleware.DecompressResponse` or `Tesla.Middleware.Compression` eagerly decompresses HTTP response bodies with no size limit. A server under attacker control (or reached via a redirect) can return a tiny gzip-encoded payload that expands into gigabytes of BEAM heap, crashing or freezing the calling process. Stacking multiple `content-encoding` tokens multiplies the amplification exponentially.

### Details

`decompress_body/2` in `lib/tesla/middleware/compression.ex` passes the full response body to `:zlib.gunzip/1` or `:zlib.unzip/1` with no cap on output size. The list of codec tokens comes from splitting the `content-encoding` header on commas, and `decompress_body/2` recurses once per token. A response advertising `content-encoding: gzip, gzip, gzip, gzip` triggers four recursive decompression passes. Each gzip layer can expand its input roughly 1000x, so a 284-byte wire payload with four layers inflates to approximately 1 GB at the innermost pass, all materialised as a single binary in the caller's heap.

### PoC

1. Serve an HTTP response with `content-encoding: gzip, gzip, gzip, gzip` where the body is a 1 GB block of zeros compressed through four successive gzip passes.
2. Send that response to a Tesla client whose pipeline includes `Tesla.Middleware.DecompressResponse`.
3. `decompress_body/2` recurses four times without any size check, materialising ~1 GB in the calling process's heap.
4. Repeated or sufficiently large requests exhaust available memory and crash or freeze the node.

### Impact

High severity (CVSS v4.0: 8.2). Any application using `tesla` 0.6.0 through 1.18.2 with `Tesla.Middleware.DecompressResponse` or `Tesla.Middleware.Compression` in its pipeline is vulnerable. The attacker only needs to control a server the client contacts, including via redirects. Fixed in tesla 1.18.3.

### Configurations

The application must include `Tesla.Middleware.DecompressResponse` or `Tesla.Middleware.Compression` in its Tesla middleware pipeline.

### Resources

* Introduction commit: https://github.com/elixir-tesla/tesla/commit/5bd90bb5cf0d15e375edc2a66fa322292940fce2
* Patch commit: https://github.com/elixir-tesla/tesla/commit/340f75b5d191dc747ef7ac6365bd002d1cd55a9d

## Affected packages

- `tesla >= 0.6.0, < 1.18.3`

## Remediation

Upgrade to a patched release:

- `tesla 1.18.3`