{"id":"GHSA-mc85-72gr-vm9f","summary":"Tesla has decompression bomb on response body","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'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","aliases":["CVE-2026-48594","EEF-CVE-2026-48594"],"modified":"2026-07-10T00:15:09.275629583Z","published":"2026-07-10T00:03:23Z","database_specific":{"severity":"HIGH","github_reviewed":true,"github_reviewed_at":"2026-07-10T00:03:23Z","nvd_published_at":"2026-06-02T20:16:38Z","cwe_ids":["CWE-409"]},"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"}],"affected":[{"package":{"name":"tesla","ecosystem":"Hex","purl":"pkg:hex/tesla"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0.6.0"},{"fixed":"1.18.3"}]}],"versions":["0.10.0","0.6.0","0.7.0","0.7.1","0.7.2","0.8.0","0.9.0","1.0.0","1.0.0-beta.1","1.1.0","1.10.0","1.10.1","1.10.2","1.10.3","1.11.0","1.11.1","1.11.2","1.12.0","1.12.1","1.12.2","1.12.3","1.13.0","1.13.1","1.13.2","1.14.0","1.14.1","1.14.2","1.14.3","1.15.0","1.15.1","1.15.2","1.15.3","1.16.0","1.17.0","1.18.0","1.18.1","1.18.2","1.2.0","1.2.1","1.3.0","1.3.1","1.3.2","1.3.3","1.4.0","1.4.1","1.4.2","1.4.3","1.4.4","1.5.0","1.5.1","1.6.0","1.6.1","1.7.0","1.8.0","1.8.1","1.9.0"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-mc85-72gr-vm9f/GHSA-mc85-72gr-vm9f.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","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"}]}