PYSEC-2026-1103

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Import Source
https://github.com/pypa/advisory-database/blob/main/vulns/aiohttp/PYSEC-2026-1103.yaml
JSON Data
https://api.osv.dev/v1/vulns/PYSEC-2026-1103
Aliases
Published
2026-07-07T14:34:45.226773Z
Modified
2026-07-07T17:46:25.745431925Z
Severity
  • 6.3 (Medium) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/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 CVSS Calculator
Summary
aiohttp allows request smuggling due to incorrect parsing of chunk extensions
Details

Summary

The Python parser parses newlines in chunk extensions incorrectly which can lead to request smuggling vulnerabilities under certain conditions.

Impact

If a pure Python version of aiohttp is installed (i.e. without the usual C extensions) or AIOHTTP_NO_EXTENSIONS is enabled, then an attacker may be able to execute a request smuggling attack to bypass certain firewalls or proxy protections.


Patch: https://github.com/aio-libs/aiohttp/commit/259edc369075de63e6f3a4eaade058c62af0df71

References

Affected packages

PyPI / aiohttp

Package

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
3.10.11

Affected versions

0.*
0.1
0.2
0.3
0.4
0.4.1
0.4.2
0.4.3
0.4.4
0.5.0
0.6.0
0.6.1
0.6.2
0.6.3
0.6.4
0.6.5
0.7.0
0.7.1
0.7.2
0.7.3
0.8.0
0.8.1
0.8.2
0.8.3
0.8.4
0.9.0
0.9.1
0.9.2
0.9.3
0.10.0
0.10.1
0.10.2
0.11.0
0.12.0
0.13.0
0.13.1
0.14.0
0.14.1
0.14.2
0.14.3
0.14.4
0.15.0
0.15.1
0.15.2
0.15.3
0.16.0
0.16.1
0.16.2
0.16.3
0.16.4
0.16.5
0.16.6
0.17.0
0.17.1
0.17.2
0.17.3
0.17.4
0.18.0
0.18.1
0.18.2
0.18.3
0.18.4
0.19.0
0.20.0
0.20.1
0.20.2
0.21.0
0.21.1
0.21.2
0.21.4
0.21.5
0.21.6
0.22.0a0
0.22.0b0
0.22.0b1
0.22.0b2
0.22.0b3
0.22.0b4
0.22.0b5
0.22.0b6
0.22.0
0.22.1
0.22.2
0.22.3
0.22.4
0.22.5
1.*
1.0.0
1.0.1
1.0.2
1.0.3
1.0.5
1.1.0
1.1.1
1.1.2
1.1.3
1.1.4
1.1.5
1.1.6
1.2.0
1.3.0
1.3.1
1.3.2
1.3.3
1.3.4
1.3.5
2.*
2.0.0rc1
2.0.0
2.0.1
2.0.2
2.0.3
2.0.4
2.0.5
2.0.6
2.0.7
2.1.0
2.2.0
2.2.1
2.2.2
2.2.3
2.2.4
2.2.5
2.3.0a1
2.3.0a2
2.3.0a3
2.3.0a4
2.3.0
2.3.1a1
2.3.1
2.3.2b2
2.3.2b3
2.3.2
2.3.3
2.3.4
2.3.5
2.3.6
2.3.7
2.3.8
2.3.9
2.3.10
3.*
3.0.0b0
3.0.0b1
3.0.0b2
3.0.0b3
3.0.0b4
3.0.0
3.0.1
3.0.2
3.0.3
3.0.4
3.0.5
3.0.6
3.0.7
3.0.8
3.0.9
3.1.0
3.1.1
3.1.2
3.1.3
3.2.0
3.2.1
3.3.0a0
3.3.0
3.3.1
3.3.2a0
3.3.2
3.4.0a0
3.4.0a3
3.4.0b1
3.4.0b2
3.4.0
3.4.1
3.4.2
3.4.3
3.4.4
3.5.0a1
3.5.0b1
3.5.0b2
3.5.0b3
3.5.0
3.5.1
3.5.2
3.5.3
3.5.4
3.6.0a0
3.6.0a1
3.6.0a2
3.6.0a3
3.6.0a4
3.6.0a5
3.6.0a6
3.6.0a7
3.6.0a8
3.6.0a9
3.6.0a11
3.6.0a12
3.6.0b0
3.6.0
3.6.1b3
3.6.1b4
3.6.1
3.6.2a0
3.6.2a1
3.6.2a2
3.6.2
3.6.3
3.7.0b0
3.7.0b1
3.7.0
3.7.1
3.7.2
3.7.3
3.7.4
3.7.4.post0
3.8.0a7
3.8.0b0
3.8.0
3.8.1
3.8.2
3.8.3
3.8.4
3.8.5
3.8.6
3.9.0b0
3.9.0b1
3.9.0rc0
3.9.0
3.9.1
3.9.2
3.9.3
3.9.4rc0
3.9.4
3.9.5
3.10.0b1
3.10.0rc0
3.10.0
3.10.1
3.10.2
3.10.3
3.10.4
3.10.5
3.10.6rc0
3.10.6rc1
3.10.6rc2
3.10.6
3.10.7
3.10.8
3.10.9
3.10.10
3.10.11rc0

Database specific

source
"https://github.com/pypa/advisory-database/blob/main/vulns/aiohttp/PYSEC-2026-1103.yaml"