# CVE-2026-61652: Zapros: Streaming decoders ignored the requested chunk size, allowing a single compressed response chunk to allocate unbounded memory (decompression bomb)

> A malicious server can cause memory exhaustion in Zapros by sending a compressed response that ignores chunk size limits, leading to denial of service.

- **Severity:** High 8.7 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 21 Sep 2026
- **Updated:** 22 Sep 2026
- **Also known as:** GHSA-6cp7-3m3c-5x5c, PYSEC-2026-4182

## What is CVE-2026-61652?

CVE-2026-61652 is a high-severity denial of service vulnerability in kap-sh zapros, published on 21 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### 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.

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling)

## Which versions are affected by CVE-2026-61652?

3 open source packages ship an affected version, including zapros.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `zapros` | PyPI | All versions | 0.14.0 |
| `zapros` | PyPI | All versions | 0.14.0 |
| `zapros` | PyPI | All versions | 0.14.0 |

## How do I fix CVE-2026-61652?

Upgrade zapros to 0.14.0 or later.

## Is CVE-2026-61652 being exploited?

There is no known exploitation of CVE-2026-61652 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-61652 and fix it if it is affected.

What it is: CVE-2026-61652 is a high-severity denial of service vulnerability in kap-sh zapros, published on 21 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-61652 in the wild and no public exploit code.

Affected packages and fixed versions:
- zapros (PyPI): affected all versions; fixed in 0.14.0
- zapros (PyPI): affected all versions; fixed in 0.14.0
- zapros (PyPI): affected all versions; fixed in 0.14.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-61652/ (Markdown: https://insights.sbomify.com/CVE-2026-61652/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-61652
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-61652
- OSV: https://osv.dev/vulnerability/CVE-2026-61652

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-61652/
Summaries are generated and may contain mistakes; the official description above is the record.