CVE-2026-34520— AIOHTTP: C parser (llhttp) accepts null bytes and control characters in response header values - header injection / security bypass
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I. Basic Information for CVE-2026-34520
Vulnerability Information
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Vulnerability Title
AIOHTTP: C parser (llhttp) accepts null bytes and control characters in response header values - header injection / security bypass
Source: NVD (National Vulnerability Database)
Vulnerability Description
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.13.4, the C parser (the default for most installs) accepted null bytes and control characters in response headers. This issue has been patched in version 3.13.4.
Source: NVD (National Vulnerability Database)
CVSS Information
N/A
Source: NVD (National Vulnerability Database)
Vulnerability Type
HTTP头部中CRLF序列转义处理不恰当(HTTP响应分割)
Source: NVD (National Vulnerability Database)
Vulnerability Title
aiohttp 注入漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
aiohttp是aio-libs开源的一个开源的用于 asyncio 和 Python 的异步 HTTP 客户端/服务器框架。 AIOHTTP 3.13.4之前版本存在注入漏洞，该漏洞源于C解析器接受响应标头中的空字节和控制字符。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
II. Public POCs for CVE-2026-34520
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Same Patch Batch · aio-libs · 2026-04-01 · 10 CVEs total
| CVE-2026-22815 | AIOHTTP: Uncapped memory usage possible through aiohttp allowing unlimited trailer headers | |
| CVE-2026-34513 | AIOHTTP: Denial of Service (DoS) via Unbounded DNS Cache in TCPConnector | |
| CVE-2026-34516 | AIOHTTP: Multipart Header Size Bypass | |
| CVE-2026-34514 | AIOHTTP: CRLF injection in multipart part content type header construction | |
| CVE-2026-34525 | AIOHTTP: Duplicate Host header accepted | |
| CVE-2026-34517 | AIOHTTP: Late size enforcement for non-file multipart fields causes memory DoS | |
| CVE-2026-34519 | AIOHTTP: HTTP response splitting via \r in reason phrase | |
| CVE-2026-34518 | AIOHTTP: Cookie and Proxy-Authorization headers leaked on cross-origin redirect | |
| CVE-2026-34515 | AIOHTTP: UNC SSRF/NTLMv2 Credential Theft/Local File Read in static resource handler on Wi |
IV. Related Vulnerabilities
Same product: aiohttp
- CVE-2026-34525
AIOHTTP: Duplicate Host header accepted - CVE-2026-34519
AIOHTTP: HTTP response splitting via \r in reason phrase - CVE-2026-34518
AIOHTTP: Cookie and Proxy-Authorization headers leaked on cr - CVE-2026-34517
AIOHTTP: Late size enforcement for non-file multipart fields - CVE-2026-34516
AIOHTTP: Multipart Header Size Bypass
Same vendor: aio-libs
- CVE-2026-34525
AIOHTTP: Duplicate Host header accepted - CVE-2026-34519
AIOHTTP: HTTP response splitting via \r in reason phrase - CVE-2026-34518
AIOHTTP: Cookie and Proxy-Authorization headers leaked on cr - CVE-2026-34517
AIOHTTP: Late size enforcement for non-file multipart fields - CVE-2026-34516
AIOHTTP: Multipart Header Size Bypass
Same weakness: CWE-113
- CVE-2026-42035
Axios: Header Injection via Prototype Pollution - CVE-2026-39971
Serendipity: Host Header Injection leads to SMTP header inje - CVE-2026-40175
Axios has Unrestricted Cloud Metadata Exfiltration via Heade - CVE-2026-34715
ewe Has Improper Neutralization of CRLF Sequences in HTTP He - CVE-2026-34519
AIOHTTP: HTTP response splitting via \r in reason phrase
V. Comments for CVE-2026-34520
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