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01 Record

CVE-2026-34516

AIOHTTP: Multipart Header Size Bypass

MediumPUBLISHEDCNA: GitHub_M
CNA base score6.6 CVSS v4.0CVSS: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

02 Description

AIOHTTP: Multipart Header Size Bypass

03 Exploitation and scoring

Exploitation
Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.
SSVC decision
  • ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
  • AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
  • Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.
CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.
EPSS probability
0.44% probability of exploitation activity in the next 30 days.
EPSS percentile
Equal to or higher than the score of 37.9% of scored records. A rank, not a probability.
NVD base score
6.6 (CVSS v4.0), scored by the NVD independently of the CNA.
NVD CVSS 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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD analysis status
Analyzed. NVD last modified this record on 2026-10-26.
Red Hat severity
Moderate. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published
2026-04-01 20:13Z7 MO AGO
Last updated
2026-04-04 03:11Z6 MO AGO
Reserved
2026-03-30
Assigning CNA
GitHub_M
Record state
PUBLISHED
Severity
Medium (CVSS 6.6)
CNA CVSS 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
Weaknesses
  • CWE-770Allocation of Resources Without Limits or ThrottlingBase
Data version
5.2
Document digest
1e9ab49075710f64c8c527862e56a2cc95847c6b227869d83d81812547ba03af

05 Affected products

VendorProductVersionsPlatforms
aio-libsaiohttp< 3.13.4—

06 References

07 Fixed in

Debian 12

  • python-aiohttp
    No fix yet

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 13

  • python-aiohttp
    No fix yet

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 14

  • python-aiohttp
    Fixed in 3.13.5-1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 25.10

  • python-aiohttp
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 26.10

  • python-aiohttp
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro 16.04 LTS

  • python-aiohttp
    Fixed in 0.20.2-1ubuntu0.1~esm1
    Available with Ubuntu Pro with Legacy support add-on: https://ubuntu.com/pro

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro 18.04 LTS

  • python-aiohttp
    Fixed in 3.0.1-1ubuntu0.1~esm7
    Available with Ubuntu Pro: https://ubuntu.com/pro

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro 22.04 LTS

  • python-aiohttp
    Fixed in 3.8.1-4ubuntu0.2+esm3
    Available with Ubuntu Pro: https://ubuntu.com/pro

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro 24.04 LTS

  • python-aiohttp
    Fixed in 3.9.1-1ubuntu0.1+esm3
    Available with Ubuntu Pro: https://ubuntu.com/pro

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro 26.04 LTS

  • python-aiohttp
    Fixed in 3.13.3-3ubuntu1+esm1
    Available with Ubuntu Pro: https://ubuntu.com/pro

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

A release or ecosystem missing from this list has no record here. It may be unaffected or not covered by the source. Source notices and licences.