CVE-2026-48594

Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in elixir-tesla tesla allows a denial of service via decompression bomb in HTTP response bodies. When Tesla.Middleware.DecompressResponse or Tesla.Middleware.Compression is included in a Tesla middleware pipeline, HTTP response bodies are decompressed eagerly with no size limit. The decompress_body/2 function in lib/tesla/middleware/compression.ex passes the entire response body to :zlib.gunzip/1 or :zlib.unzip/1 without any cap on the output size. Additionally, compression_algorithms/1 splits the content-encoding header on commas and decompress_body/2 recurses once per token, applying a decompression pass on each iteration. A server advertising content-encoding: gzip, gzip, gzip, gzip causes four recursive decompression passes, yielding exponential amplification: each gzip layer can expand its input roughly 1000x, so a payload of a few hundred bytes on the wire inflates to gigabytes of BEAM heap, exhausting memory and crashing or freezing the calling process. This issue affects tesla: from 0.6.0 before 1.18.3.

### 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

### 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

Vulnerabilidad de Manejo Inadecuado de Datos Altamente Comprimidos (Amplificación de Datos) en elixir-tesla tesla permite una denegación de servicio a través de una bomba de descompresión en los cuerpos de respuesta HTTP. Cuando Tesla.Middleware.DecompressResponse o Tesla.Middleware.Compression se incluye en una tubería de middleware de Tesla, los cuerpos de respuesta HTTP se descomprimen de forma ávida sin límite de tamaño. La función decompress_body/2 en lib/tesla/middleware/compression.ex pasa el cuerpo completo de la respuesta a :zlib.gunzip/1 o :zlib.unzip/1 sin ningún límite en el tamaño de salida. Además, compression_algorithms/1 divide el encabezado content-encoding por comas y decompress_body/2 recurre una vez por token, aplicando un paso de descompresión en cada iteración. Un servidor que anuncia content-encoding: gzip, gzip, gzip, gzip causa cuatro pases de descompresión recursivos, lo que resulta en una amplificación exponencial: cada capa gzip puede expandir su entrada aproximadamente 1000 veces, por lo que una carga útil de unos pocos cientos de bytes en la red se infla a gigabytes de pila BEAM, agotando la memoria y bloqueando o congelando el proceso de llamada. Este problema afecta a tesla: desde 0.6.0 antes de 1.18.3.