Vulnerability · Published Sep 21, 2026 · Assigned by GitHub_M
CVE-2026-61652Zapros: Streaming decoders ignored the requested chunk size, allowing a single compressed response chunk to allocate unbounded memory (decompression bomb)
High 8.7
In plain English
A high-severity resource allocation without limits in zapros from kap-sh. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 38% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| PyPI | zapros | 0.14.0 | GHSA-6cp7-3m3c-5x5c |
| PyPI | zapros | 0.14.0 | PYSEC-2026-4182 |
Affected products (as reported)
Weakness: CWE-770 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
References
- https://github.com/kap-sh/zapros/security/advisories/GHSA-6cp7-3m3c-5x5c x_refsource_CONFIRM