{"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","slug":"CVE-2026-48594","body":"## Overview\n\n### 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's 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's 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\n\n## Affected packages\n\n- `tesla >= 0.6.0, < 1.18.3`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `tesla 1.18.3`","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}