Is CVE-2026-34519 in the CISA KEV catalog?

No. CVE-2026-34519 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-34519?

CVE-2026-34519 has a CVSS v3 base score of 5.3 (MEDIUM).

What is the EPSS score for CVE-2026-34519?

CVE-2026-34519 has an EPSS score of 0.29% (21th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-34519?

Upgrade python-aiohttp on debian 11 to 3.7.4-1+deb11u2 or later.

CVE & CISA-KEV Catalog

CVE-2026-34519

MEDIUM

5.3

CVSS v3

NVD

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.

CWE-113

How to fix

Remediation Available

python-aiohttpDebian

Fixed in:3.7.4-1+deb11u2CVE-2026-34519

Fixed in:3.13.5-1CVE-2026-34519

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityLow

AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Exploit Intelligence

0.29%probability of exploitation in 30 days

21stpercentile

Low risk: more likely to be exploited than 21% of all known CVEs.

References

Patch2

Release Notes1

github.com

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-04-16.