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High · 8.7 CVE-2026-61652 EUVD-2026-84175GHSA-6cp7-3m3c-5x5cPYSEC-2026-4182

Zapros: Streaming decoders ignored the requested chunk size, allowing a single compressed response chunk to allocate unbounded memory (decompression bomb)

Published Sep 21, 2026 · Updated Sep 22, 2026 · Assigned by GitHub_M

Description

Zapros, a Python HTTP client, prior to version 0.14.0 is vulnerable to denial of service via memory exhaustion. The issue 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. Version 0.14.0 contains a patch. Some workarounds are available. 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.

Affected products

VendorProductAffectedFixed
kap-sh zapros < 0.14.0 —

Affected packages

EcosystemPackageAffectedFixedRecord
PyPI zapros < 0.14.0 0.14.0 GHSA-6cp7-3m3c-5x5c

References