# CVE-2026-54278: aio-libs aiohttp Denial of Service via compressed request body decompression

Source: https://junglewise.ai/threats/cve-2026-54278-aio-libs-aiohttp-denial-of-service-via-compressed-request-body  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-22. Updated: 2026-06-22  
License: CC BY 4.0 with a link back

CVE-2026-54278 · Severity: medium · CVSS 4 · Published 2026-06-22

AIOHTTP is a popular Python library used by developers to build web servers and handle web requests. A flaw in how the library handles compressed data allows an attacker to send a specially crafted "zip bomb" that expands to a massive size in the server's memory during cleanup. This can exhaust the server's resources, causing the application to crash or become unresponsive to legitimate users.

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

## Quick answers

**Is CVE-2026-54278 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-54278 being exploited in the wild.

**How severe is CVE-2026-54278?** Medium severity, with a CVSS score of 4, published 22 June 2026.

**Which products and versions are affected?** aiohttp (PyPI) <= 3.14.0, ECOSYSTEM:introduced=0,fixed=3.14.1.

**Is there a fix for CVE-2026-54278?** Yes. aiohttp (PyPI): upgrade to 3.14.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-54278 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-54278?** 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 3.14.1 or later

  ```sh
  pip install "aiohttp>=3.14.1"
  ```


## Technical details

AIOHTTP is vulnerable to a Denial of Service (DoS) via a data amplification (zip bomb) attack. The vulnerability exists in the cleanup logic where unread compressed request bodies are decompressed into memory in a single chunk, bypassing 'client_max_size' restrictions. An unauthenticated remote attacker can exploit this by sending a highly compressed payload that expands significantly upon decompression, leading to memory exhaustion. This issue is classified as CWE-409 (Improper Handling of Highly Compressed Data). The vulnerability is fixed in version 3.14.1 by implementing bounded unread compressed drains.

## Affected products

- aio-libs aiohttp < 3.14.1

## Identifiers

- CVE-2026-54278
- GHSA-g3cq-j2xw-wf74
- PYSEC-2026-2111

## Timeline

- 2026-06-08: advisory: GitHub Security Advisory GHSA-g3cq-j2xw-wf74 published
- 2026-06-22: disclosed: CVE-2026-54278 published to NVD
- 2026-06-22: patched: Fix released in version 3.14.1

## References

- [https://github.com/aio-libs/aiohttp/commit/4f7480e474cccc6a8cc2c92ad3f17a31dedf8232](https://github.com/aio-libs/aiohttp/commit/4f7480e474cccc6a8cc2c92ad3f17a31dedf8232)
- [https://github.com/aio-libs/aiohttp/security/advisories/GHSA-g3cq-j2xw-wf74](https://github.com/aio-libs/aiohttp/security/advisories/GHSA-g3cq-j2xw-wf74)

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