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.

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

Q: Which products and versions are affected?

aiohttp (PyPI) <= 3.14.0, ECOSYSTEM:introduced=0,fixed=3.14.1.

Q: 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.

Q: How is CVE-2026-54278 attacked?

It is attacked over the network, in a software library.

Q: 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.

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). 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
```
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

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