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.

How to fix

Remediation Available
python-aiohttpDebian
Fixed in:3.13.5-1CVE-2026-34519

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

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
22ndpercentile

Low risk: more likely to be exploited than 22% of all known CVEs.

References

Release Notes1

Related Vulnerabilities

Other CWE-113 vulnerabilities, ordered by exploit likelihood. View all

CVESeverityCVSSEPSSExploitedFix
CVE-2022-37436Medium5.361%-Fix
CVE-2024-52875High8.830%--
CVE-2016-5699Medium6.19.9%-Fix
CVE-2016-8024High8.18.7%--
CVE-2017-17742Medium5.35.5%-Fix
CVE-2016-5325Medium6.14.1%-Fix

Common questions

How do I fix CVE-2026-34519?

Upgrade python-aiohttp on debian unstable to 3.13.5-1 or later.

Is CVE-2026-34519 being actively exploited?

Not that we know of. CVE-2026-34519 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.29% is the estimated probability that it will be exploited in the next 30 days. That is higher than 22% of all scored CVEs.

How severe is CVE-2026-34519?

CVE-2026-34519 has a CVSS v3 base score of 5.3, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2026-34519 affect?

Published advisories record a fix for python-aiohttp (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

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CVE-2026-34519 severity badge

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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 2026-06-17.