VDB-354771 · CVE-2026-34519 · GHSA-mwh4-6h8g-pg8w

aio-libs aiohttp up to 3.13.3 Reason response splitting

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
5.1	$0-$5k	0.00

Summaryinfo

A vulnerability marked as problematic has been reported in aio-libs aiohttp up to 3.13.3. Affected is an unknown function. Performing a manipulation of the argument Reason results in response splitting. This vulnerability is identified as CVE-2026-34519. The attack can be initiated remotely. There is not any exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic has been found in aio-libs aiohttp up to 3.13.3. This affects an unknown code. The manipulation of the argument reason with an unknown input leads to a response splitting vulnerability. CWE is classifying the issue as CWE-113. The product receives data from an HTTP agent/component (e.g., web server, proxy, browser, etc.), but it does not neutralize or incorrectly neutralizes CR and LF characters before the data is included in outgoing HTTP headers. This is going to have an impact on integrity. The summary by CVE is:

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.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-34519 since 03/30/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details of the vulnerability are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 318080 (Debian dla-4613 : python-aiohttp-doc - security update), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 3.13.4 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying the patch 53b35a2f8869c37a133e60bf1a82a1c01642ba2b is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at CNNVD (CNNVD-202604-220) and Tenable (318080). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Vendor

aio-libs

Name

aiohttp

Version

License

open-source

Website

Product: https://github.com/aio-libs/aiohttp/

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 5.3
VulDB Meta Temp Score: 5.1

VulDB Base Score: 5.3
VulDB Temp Score: 5.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AV	AC	Au	C	I	A
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Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Response splitting
CWE: CWE-113 / CWE-93 / CWE-74
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Nessus ID: 318080
Nessus Name: Debian dla-4613 : python-aiohttp-doc - security update

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: aiohttp 3.13.4
Patch: 53b35a2f8869c37a133e60bf1a82a1c01642ba2b

Timelineinfo

03/30/2026 CVE reserved
04/02/2026 +3 days Advisory disclosed
04/02/2026 +0 days VulDB entry created
06/01/2026 +60 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: GHSA-mwh4-6h8g-pg8w
Status: Confirmed

CVE: CVE-2026-34519 (🔒)
GCVE (CVE): GCVE-0-2026-34519
GCVE (VulDB): GCVE-100-354771
CNNVD: CNNVD-202604-220 - aiohttp 注入漏洞

Entryinfo

Created: 04/02/2026 02:33
Updated: 06/01/2026 21:00
Changes: 04/02/2026 02:33 (71), 04/02/2026 18:48 (6), 06/01/2026 21:00 (2)
Complete: 🔍
Cache ID: 216::103

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.