CVE-2026-61652

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

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.

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.

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

The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap. Typical impact: resource exhaustion leading to denial of service.

Kodem intelligence

Already deployed Kodem?

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.

1. What is CVE-2026-61652? CVE-2026-61652 is a high-severity allocation of resources without limits or throttling vulnerability in zapros (pip), affecting versions < 0.14.0. It is fixed in 0.14.0. The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap.
2. Which versions of zapros are affected by CVE-2026-61652? zapros (pip) versions < 0.14.0 is affected.
3. Is there a fix for CVE-2026-61652? Yes. CVE-2026-61652 is fixed in 0.14.0. Upgrade to this version or later.
4. Is CVE-2026-61652 exploitable, and should I be worried? Whether CVE-2026-61652 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
5. What actually determines whether CVE-2026-61652 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
6. How do I fix CVE-2026-61652? Upgrade zapros to 0.14.0 or later.

Other vulnerabilities in zapros