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CVE-2026-123817

8.7 highEPSS 0.3%Fix available

High (8.7) in aio-libs aiohttp. EPSS 0.3% estimated probability of exploitation activity in the next 30 days. Fixed in aiohttp 3.14.4.

On this page
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.4, the WebSocket reader retains one bytes object for each transport read while reassembling an incomplete frame. A malicious peer can split a frame into many tiny reads so per-object overhead substantially exceeds the payload bytes allowed by max_msg_size. The condition affects a server receiving frames from a malicious client and a client receiving frames from a malicious server, and can cause excessive memory consumption or denial of service. This issue is fixed in version 3.14.4.

Severity

CVSS 4.0

8.7 high
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
EPSS
0.3% estimated probability of exploitation activity in the next 30 days; 26th percentile. Scored 2026-11-10. A forecast for this CVE across the internet, not for your own systems.
CWE
CWE-770 Allocation of Resources Without Limits or Throttling
Published
Assigned by
GitHub_M (CNA)
NVD analysis
Not in the NVD yet
Record from
the CVE List, synced

Ask an AI about this CVE

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Affected

Versions

From the CNA's record in the CVE List.

ProductAffected
aio-libs aiohttp< 3.14.4

Packages (OSV)

AdvisoryEcosystemPackageAffectedFixed in
GHSA-2g87-pp6c-29x5PyPIaiohttp<3.14.43.14.4

Linux distributions

DistributionReleasePackageFixed inAdvisory
Debian12, 13, 14python-aiohttpno fix listedDEBIAN-CVE-2026-123817

From the distributions' data via OSV.dev: the Debian Security Tracker. Modified: reformatted and linked to CVE records. Credits. On the distributions' own pages: Debian.

Attack patterns (CAPEC)

The attack patterns MITRE's CAPEC relates to this record's weaknesses, as MITRE names them. Credits. More on the page of CWE-770 (20).

References

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