GHSA-MC85-72GR-VM9F
Vulnerability from github – Published: 2026-07-10 00:03 – Updated: 2026-07-10 00:03Summary
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
- Serve an HTTP response with
content-encoding: gzip, gzip, gzip, gzipwhere the body is a 1 GB block of zeros compressed through four successive gzip passes. - Send that response to a Tesla client whose pipeline includes
Tesla.Middleware.DecompressResponse. decompress_body/2recurses four times without any size check, materialising ~1 GB in the calling process's heap.- 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": [
{
"package": {
"ecosystem": "Hex",
"name": "tesla"
},
"ranges": [
{
"events": [
{
"introduced": "0.6.0"
},
{
"fixed": "1.18.3"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-48594"
],
"database_specific": {
"cwe_ids": [
"CWE-409"
],
"github_reviewed": true,
"github_reviewed_at": "2026-07-10T00:03:23Z",
"nvd_published_at": "2026-06-02T20:16:38Z",
"severity": "HIGH"
},
"details": "### Summary\n\nAny 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.\n\n### Details\n\n`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\u0027s heap.\n\n### PoC\n\n1. 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.\n2. Send that response to a Tesla client whose pipeline includes `Tesla.Middleware.DecompressResponse`.\n3. `decompress_body/2` recurses four times without any size check, materialising ~1 GB in the calling process\u0027s heap.\n4. Repeated or sufficiently large requests exhaust available memory and crash or freeze the node.\n\n### Impact\n\nHigh 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.\n\n### Configurations\n\nThe application must include `Tesla.Middleware.DecompressResponse` or `Tesla.Middleware.Compression` in its Tesla middleware pipeline.\n\n### Resources\n\n* Introduction commit: https://github.com/elixir-tesla/tesla/commit/5bd90bb5cf0d15e375edc2a66fa322292940fce2\n* Patch commit: https://github.com/elixir-tesla/tesla/commit/340f75b5d191dc747ef7ac6365bd002d1cd55a9d",
"id": "GHSA-mc85-72gr-vm9f",
"modified": "2026-07-10T00:03:23Z",
"published": "2026-07-10T00:03:23Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/elixir-tesla/tesla/security/advisories/GHSA-mc85-72gr-vm9f"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-48594"
},
{
"type": "WEB",
"url": "https://github.com/elixir-tesla/tesla/commit/340f75b5d191dc747ef7ac6365bd002d1cd55a9d"
},
{
"type": "WEB",
"url": "https://cna.erlef.org/cves/CVE-2026-48594.html"
},
{
"type": "PACKAGE",
"url": "https://github.com/elixir-tesla/tesla"
},
{
"type": "WEB",
"url": "https://osv.dev/vulnerability/EEF-CVE-2026-48594"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "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",
"type": "CVSS_V4"
}
],
"summary": "Tesla has decompression bomb on response body"
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
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- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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