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Fencer Vulns
medium 5.3

CVE-2023-37276 json

aiohttp vulnerable to HTTP request smuggling

published 2023-07-19 3 y ago modified 2026-09-10 1 mo ago also GHSA-45c4-8wx5-qw6w , PYSEC-2023-120 , EUVD-2023-0003

cvss
5.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.3%
EPSS 1.3% chance of exploitation in 30 days, percentile 71%
public exploits
0
none known

Summary

aiohttp is an asynchronous HTTP client/server framework for asyncio and Python. aiohttp v3.8.4 and earlier are bundled with llhttp v6.0.6. Vulnerable code is used by aiohttp for its HTTP request parser when available which is the default case when installing from a wheel. This vulnerability only affects users of aiohttp as an HTTP server (ie `aiohttp.Application`), you are not affected by this vulnerability if you are using aiohttp as an HTTP client library (ie `aiohttp.ClientSession`). Sending a crafted HTTP request will cause the server to misinterpret one of the HTTP header values leading to HTTP request smuggling. This issue has been addressed in version 3.8.5. Users are advised to upgrade. Users unable to upgrade can reinstall aiohttp using `AIOHTTP_NO_EXTENSIONS=1` as an environment variable to disable the llhttp HTTP request parser implementation. The pure Python implementation isn't vulnerable.

Patch / fix

  • pypi aiohttp 3.8.5
  • aio-libs_project aiohttp 3.8.5
  • python-aiohttp Debian 14, Debian 13 3.8.5-1

debian advisories DEBIAN-CVE-2023-37276

  • foreman satellite utils 6.15, satellite capsule 6.15, satellite 6.15 3.9.1.6-1.el8sat
  • foreman-cli satellite utils 6.15, satellite 6.15 3.9.1.6-1.el8sat
  • foreman-ec2 satellite 6.15 3.9.1.6-1.el8sat
  • foreman-pcp satellite 6.15 3.9.1.6-1.el8sat
  • puppetserver satellite capsule 6.15, satellite 6.15 7.14.0-1.el8sat
  • rubygem-puma satellite 6.15 6.4.2-1.el8sat
  • foreman-ovirt satellite 6.15 3.9.1.6-1.el8sat
  • foreman-redis satellite 6.15 3.9.1.6-1.el8sat

red hat advisories RHSA-2024:2010RHSA-2024:1878

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2023-37276 updated cvss 7.5

python-aiohttp: HTTP request smuggling via llhttp HTTP request parser

  • Red Hat Ansible Automation Platform 1.2 python-aiohttp
    affected: no fix planned “Will not fix”
  • Red Hat Ansible Automation Platform 2 python-aiohttp Red Hat OpenShift Data Science (RHODS) python-aiohttp
    affected: no fix available
  • Red Hat OpenStack Platform 17.1 python-aiohttp
    affected: no fix planned “Will not fix”
  • Red Hat Satellite 6.15 for RHEL 8 python-aiohttp 3.9.2-1.el8pc, python3.11-aiohttp 3.9.2-1.el8pc
    fixed: vendor fix RHSA-2024:2010
  • Red Hat RHUI 4 for RHEL 8 python-aiohttp 3.9.2-1.el8ui
    fixed: vendor fix RHSA-2024:1878
  • Red Hat Satellite 6.15 for RHEL 8 cjson 1.7.14-5.el8sat, libsolv 0.7.22-6.el8pc, katello 4.11.0-1.el8sat, libcomps 0.1.18-8.el8pc, python-jq 1.6.0-3.el8pc, foreman 3.9.1.6-1.el8sat, +677 more Red Hat RHUI 4 for RHEL 8 libsolv 0.7.22-6.el8ui, libcomps 0.1.18-8.el8ui, python-jq 1.6.0-3.el8ui, python-xlrd 2.0.1-8.el8ui, python-xlwt 1.3.0-6.el8ui, python-yarl 1.8.2-4.el8ui, +202 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
2 y ago

Exploit prediction

1.34% chance of exploitation in the next 30 days, higher than 71% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/aio-libs/aiohttp/security/advisories/GHSA-45c4-8wx5-qw6w referenced PoC, tagged "exploit" by a source, unverified
  • hackerone.com https://hackerone.com/reports/2001873 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
GitHub 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Affected packages

ecosystem package affected fixed in
pypi aiohttp
<3.8.5
3.8.5

Affected products

  • aio-libs aiohttp
  • aio-libs_project aiohttp

Classification

Weakness
  • CWE-444 Inconsistent Interpretation of HTTP Requests

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.