GHSA-6cp7-3m3c-5x5c
Zapros: Streaming decoders ignored the requested chunk size, allowing a single compressed response chunk to allocate unbounded memory (decompression bomb)
Quick fix
GHSA-6cp7-3m3c-5x5c — zapros: upgrade to the fixed version with the command below.
pip install --upgrade 'zapros>=0.14.0'Details
### Impact
Denial of service via memory exhaustion. Affects all callers who streamed compressed responses relying on the chunk size — explicit (`iter_bytes(chunk_size=...)`) or the default — to bound memory. The decoder ignored that bound, so a chunk could be far larger than requested and a single compressed response could overflow memory.
```python import gzip, zapros
# Server returns ~1 GiB of zeros gzip-compressed to ~1 MiB, # with header: Content-Encoding: gzip bomb = gzip.compress(b"\0" * 1_000_000_000) # ~1 MiB on the wire
with zapros.stream("GET", "https://malicious.example/bomb") as response: # Caller asks for 8 KiB chunks, expecting bounded memory: for chunk in response.iter_bytes(chunk_size=8192): ... # first `chunk` is ~1 GiB, not 8 KiB -> memory exhaustion ```
### Patches
Upgrade to `0.14.0` or later. The decoders now bound the output of each decompression step to the requested `chunk_size`: gzip/deflate via `zlib`'s `max_length` + `unconsumed_tail`, brotli via `output_buffer_limit`, and zstd via a bounded `stream_writer`. Peak memory during streaming decode is now proportional to `chunk_size` for all supported encodings.
### Workarounds
For unpatched versions: - Read the still-compressed body with `Response.iter_raw()` / `Response.async_iter_raw()`, which bypass the built-in decoders, and decompress it yourself with an explicit output-size bound (e.g. `zlib`'s `max_length`), aborting once a configured limit is exceeded. - Where feasible, send `Accept-Encoding: identity` to disable response compression so bodies are not decompressed client-side. - Avoid decoding response bodies from untrusted servers.
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Affected packages
References
- https://github.com/kap-sh/zapros/security/advisories/GHSA-6cp7-3m3c-5x5c[WEB]
- https://nvd.nist.gov/vuln/detail/CVE-2026-61652[ADVISORY]
- https://github.com/kap-sh/zapros/commit/9b59fa65857734599c34b0b3dff4c2b62293a68d[WEB]
- https://github.com/kap-sh/zapros[PACKAGE]
- https://github.com/kap-sh/zapros/releases/tag/v0.14.0[WEB]