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VulnerabilityPublished

CVE-2026-128127: aio-libs aiohttp · Uncontrolled Resource Consumption

Affects aio-libs aiohttpSource CVE Database V5

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Not known to be exploited · CVSS 8.7 High : upgrade to 3.14.4 soon.

Data as of 13 Nov 2026, 20:48 UTC

CVSS 4.0 base score
8.7High
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (GitHub_M)CVSS 4.08.7
Patch
Available – fixed in 3.14.4
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

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 13 Nov 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 13 Nov 2026.

What to do

Upgrade aio-libs aiohttp to 3.14.4.

Affected software

ProductAffectedFixed in
aio-libsaiohttpAffected
  • <3.14.4
Fixed in
  • 3.14.4

AI-suggested

Upgrade aiohttp to version 3.14.4 or later, where this vulnerability is fixed. No other mitigations are indicated by the vendor advisory.

Description

CVE-2026-128127 is a high-severity vulnerability in aiohttp prior to version 3.14.4. The issue occurs in BodyPartReader.read_chunk() when processing multipart parts with Content-Transfer-Encoding set to base64. The function reads until the chunk length is a multiple of four without enforcing a byte limit, which can lead to uncontrolled resource consumption. This allows a remote attacker to send specially crafted multipart requests that bypass client_max_size limits, potentially causing excessive memory use or event loop spinning. The vulnerability is fixed in aiohttp version 3.14.4.

References

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