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Fencer Vulns
low 3.4

CVE-2023-47641 json

Inconsistent interpretation of `Content-Length` vs. `Transfer-Encoding` in aiohttp

published 2023-11-14 2 y ago modified 2026-06-17 4 mo ago also GHSA-xx9p-xxvh-7g8j , PYSEC-2023-247 , EUVD-2023-0005

cvss
3.4
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.8%
EPSS 0.8% chance of exploitation in 30 days, percentile 57%
public exploits
0
none known

Summary

aiohttp is an asynchronous HTTP client/server framework for asyncio and Python. Affected versions of aiohttp have a security vulnerability regarding the inconsistent interpretation of the http protocol. HTTP/1.1 is a persistent protocol, if both Content-Length(CL) and Transfer-Encoding(TE) header values are present it can lead to incorrect interpretation of two entities that parse the HTTP and we can poison other sockets with this incorrect interpretation. A possible Proof-of-Concept (POC) would be a configuration with a reverse proxy(frontend) that accepts both CL and TE headers and aiohttp as backend. As aiohttp parses anything with chunked, we can pass a chunked123 as TE, the frontend entity will ignore this header and will parse Content-Length. The impact of this vulnerability is that it is possible to bypass any proxy rule, poisoning sockets to other users like passing Authentication Headers, also if it is present an Open Redirect an attacker could combine it to redirect random users to another website and log the request. This vulnerability has been addressed in release 3.8.0 of aiohttp. Users are advised to upgrade. There are no known workarounds for this vulnerability.

Patch / fix

  • pypi aiohttp 3.8.0
  • aiohttp aiohttp 3.8.0
  • python-aiohttp Debian 14, Debian 13, Debian 12 3.8.1-1

debian advisories DEBIAN-CVE-2023-47641

  • python-aiohttp SLES for SAP 15 SP4, SLES 15 SP4-LTSS, SLE Module for Python 3 15 SP5 +3 more 3.9.3-150400.10.14.1
  • python-aiohttp SLE Module for Public Cloud 15 SP5, SLE Module for Public Cloud 15 SP4, SLE Module for Public Cloud 15 SP3 +4 more 3.6.0-150100.3.12.1

suse advisories SUSE-SU-2024:0577-1SUSE-SU-2023:4909-1

  • python-aiohttp openSUSE Tumbleweed 3.14.3-1.1
  • python-aiohttp openSUSE Tumbleweed 3.9.3-2.1

opensuse advisories openSUSE-SU-2026:11467-1openSUSE-SU-2024:13691-1

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-2023-47641 updated cvss 3.4

python-aiohttp: inconsistent interpretation of `Content-Length` vs. `Transfer-Encoding`

  • Red Hat Ansible Automation Platform 2 python-aiohttp, python3x-aiohttp Red Hat Satellite 6 python-aiohttp, python3-aiohttp Red Hat Update Infrastructure 4 for Cloud Providers python-aiohttp
    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
none
Automatable
no
Technical impact
partial
Assessed
2 y ago

Exploit prediction

0.83% chance of exploitation in the next 30 days, higher than 57% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/aio-libs/aiohttp/security/advisories/GHSA-xx9p-xxvh-7g8j referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 3.4 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:N/A:N
NVD 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
OSV 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
GitHub 3.1 3.4 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:N/A:N

Affected packages

ecosystem package affected fixed in
pypi aiohttp
<3.8.0
3.8.0

Affected products

  • aio-libs 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.