CVE-2026-34519

AIOHTTP: HTTP response splitting via \r in reason phrase

At a glance

Severity: LOW 2.7
EPSS: EPSS 0.29 % · percentile 22 (2026-10-27)
State: PUBLISHED
Published: 2026-04-01
Updated: 2026-04-02
Assigner: GitHub_M
NVD status: Analyzed

Description

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.13.4, an attacker who controls the reason parameter when creating a Response may be able to inject extra headers or similar exploits. This issue has been patched in version 3.13.4.

Scores

Version	Score	Vector	Scored by
CVSS 4.0	LOW 2.7	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U	GitHub_M
CVSS 4.0	LOW 2.7	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/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 · security-advisories@github.com (Secondary)
CVSS 3.1	MEDIUM 5.3	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N	NVD · nvd@nist.gov (Primary)

Weaknesses (CWE)

CWE-113

Advisories

GHSA-mwh4-6h8g-pg8w — AIOHTTP has HTTP response splitting via \r in reason phrase
PYSEC-2026-2101 — AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.13.4, an attacker who controls the reason parameter when crea

European references

ENISA EUVD · EUVD-2026-18044
GCVE · GCVE-0-2026-34519

CERT-FR advisories

CERTFR-2026-AVI-1385 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr
CERTFR-2026-AVI-1094 — Multiples vulnérabilités dans les produits IBM · cert.ssi.gouv.fr
CERTFR-2026-AVI-1056 — Multiples vulnérabilités dans les produits Splunk · cert.ssi.gouv.fr
CERTFR-2026-AVI-0556 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr
CERTFR-2026-AVI-0550 — Multiples vulnérabilités dans les produits IBM · cert.ssi.gouv.fr

Affected configurations (NVD CPE)

cpe:2.3:a:aiohttp:aiohttp:*:*:*:*:*:*:*:* < 3.13.4

Affected products

Product	Versions
aio-libs · aiohttp	affected < 3.13.4

References

Sources

Source	Licence
CVE List (CVEProject cvelistV5)	CVE Program Terms of Use
EPSS (FIRST.org)	FIRST — attribution requested
ENISA EUVD	ENISA — reproduction authorised, source acknowledged
CERT-FR (ANSSI)	Licence Ouverte / Etalab 2.0
NVD (NIST) via fkie-cad/nvd-json-data-feeds	Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD