cve.bz

CVE-2026-128131 AIOHTTP: Concatenated compressed streams cause excessive CPU use

8.7 high

High (8.7) in aio-libs aiohttp.

On this page
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.4, aiohttp decompresses each member of a payload containing many concatenated gzip, deflate, or zstd streams by passing the entire remaining input to a new decompressor, causing quadratic CPU use. Empty members produce no output, so client_max_size and output backpressure do not limit the work. A remote attacker can block a server event loop with a crafted compressed request body or WebSocket message, and a malicious server can similarly block a client. 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
CWEs
CWE-400 Uncontrolled Resource Consumption
CWE-407 Inefficient Algorithmic Complexity
Published
Modified
Assigned by
GitHub_M (CNA)
NVD analysis
Awaiting analysis
Record from
the NVD, synced

Ask an AI about this CVE

ChatGPTClaudeGoogle AI Mode

Show the promptExplain CVE-2026-128131 for an engineer deciding whether to act. Use https://cve.bz/api/public/cves/CVE-2026-128131?via=ask-ai-copy and https://cve.bz/cve/CVE-2026-128131?via=ask-ai-copy as the source of truth: what is affected and which versions fix it, whether it is in CISA KEV, public exploits, and its EPSS (an internet-wide 30-day estimate of exploitation activity, not a forecast for my systems). If they give no fixed versions, use the CVE record https://cveawg.mitre.org/api/cve/CVE-2026-128131 or the vendor advisory, not third-party mirrors. Tell me how to check whether I am affected and how to verify a fix. Cite the sources and say where they are uncertain.

Opens a third-party assistant; its answer is its own, not cve.bz's. The prompt holds only this CVE's id and public links.

Badge for a README or a site

CVE-2026-128131

An image that stays current: it is drawn from the data each time it is fetched (a host that proxies images, as GitHub does, may show its copy for a while). Markdown:

[![CVE-2026-128131](https://cve.bz/cve/badge/CVE-2026-128131.svg)](https://cve.bz/cve/CVE-2026-128131)

HTML:

<a href="https://cve.bz/cve/CVE-2026-128131"><img src="https://cve.bz/cve/badge/CVE-2026-128131.svg" alt="CVE-2026-128131"></a>

Affected

Versions

From the CNA's record in the CVE List.

ProductAffected
aio-libs aiohttp< 3.14.4

Attack patterns (CAPEC)

  • CAPEC-147 XML Ping of the Death Likelihood: Low · Severity: Medium
  • CAPEC-227 Sustained Client Engagement
  • CAPEC-492 Regular Expression Exponential Blowup

The attack patterns MITRE's CAPEC relates to this record's weaknesses, as MITRE names them. Credits.

References

Check your stackJSON