# CVE-2025-53643: PYSEC-2026-1104 - AIOHTTP is vulnerable to HTTP Request/Response Smuggling through incorrect parsing of chunked trailer sections

Source: https://junglewise.ai/threats/cve-2025-53643-aiohttp-is-vulnerable-to-http-request-response-smuggling-through  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-07  
License: CC BY 4.0 with a link back

CVE-2025-53643 · Severity: medium · CVSS 4 · Published 2026-07-07

AIOHTTP is vulnerable to HTTP Request/Response Smuggling through incorrect parsing of chunked trailer sections

Technologies: [aiohttp (PyPI)](https://junglewise.ai/threats/technologies/aiohttp). Vendors: [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is CVE-2025-53643 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2025-53643 being exploited in the wild.

**How severe is CVE-2025-53643?** Medium severity, with a CVSS score of 4, published 7 July 2026.

**Which products and versions are affected?** aiohttp (PyPI) ECOSYSTEM:introduced=0,fixed=3.12.14.

**Is there a fix for CVE-2025-53643?** Yes. aiohttp (PyPI): upgrade to 3.12.14 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**Am I affected by CVE-2025-53643?** Check whether you run aiohttp (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- aiohttp (PyPI): upgrade to 3.12.14 or later

  ```sh
  pip install "aiohttp>=3.12.14"
  ```


## Affected products

- aiohttp (PyPI) ECOSYSTEM:introduced=0,fixed=3.12.14

## Identifiers

- CVE-2025-53643
- GHSA-9548-qrrj-x5pj
- PYSEC-2026-1104

## Related threats

- [aiohttp HTTP request smuggling in pure Python parser](https://junglewise.ai/threats/cve-2026-111750-aiohttp-is-an-asynchronous-http-client-server-framework-for)
- [aiohttp host-only cookie scope bypass in subdomain handling](https://junglewise.ai/threats/cve-2026-111749-aiohttp-is-an-asynchronous-http-client-server-framework-for)
- [aiohttp Request scheme manipulation in absolute-form requests](https://junglewise.ai/threats/cve-2026-111748-aiohttp-is-an-asynchronous-http-client-server-framework-for)
- [AIOHTTP multipart request file descriptor exhaustion](https://junglewise.ai/threats/cve-2026-111066-aiohttp-is-an-asynchronous-http-client-server-framework-for)
- [aiohttp cookie Max-Age integer overflow causes connection pool exhaustion](https://junglewise.ai/threats/cve-2026-111065-aiohttp-is-an-asynchronous-http-client-server-framework-for)