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Vulnerability · Published Jun 22, 2026 · Assigned by GitHub_M

CVE-2026-54278AIOHTTP: Unread Compressed Request Bodies Bypass client_max_size During Cleanup

Medium 6.6

In plain English

A medium-severity security flaw in aiohttp from aio-libs. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 43% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)6.6Medium
Exploit odds (30 days)0.5%top 57.4% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.1, during cleanup it is possible for a compressed request body to be decompressed into memory in one chunk. An attacker may be able to send a compressed payload in specific situations that could be decompressed into memory, potentially leading to DoS (a zip bomb edge case). This vulnerability is fixed in 3.14.1.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:13python-aiohttpno fix listedDEBIAN-CVE-2026-54278
Debian:14python-aiohttp3.14.1-1DEBIAN-CVE-2026-54278
PyPIaiohttp3.14.1GHSA-g3cq-j2xw-wf74
PyPIaiohttp3.14.1PYSEC-2026-2111
Ubuntu:25.10python-aiohttpno fix listedUBUNTU-CVE-2026-54278
Ubuntu:26.10python-aiohttpno fix listedUBUNTU-CVE-2026-54278

Affected products (as reported)

VendorProductVersions
aio-libs aiohttp < 3.14.1

Weakness: CWE-409 · Vector: 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/E:U

References