CVE-2026-121727— Kore before 4.3.0 Integer Underflow Memory Exhaustion via http_header_recv()
Quick assessment
Affected
jorisvink kore
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.
Kore 4.3.0 之前的版本在 HTTP 请求体处理中存在一个整数下溢漏洞。该漏洞允许未认证的攻击者通过发送超过声明大小的请求体字节数，绕过 限制。攻击者可以利用多个并发的 POST、PUT 或 DELETE 连接，发送过大的首个数据段，导致 发生回绕（wrap-around），从而使缓冲区无限制增长，最终耗尽工作进程（worker）的内存。
Possible ATT&CK Techniques 2 AI
T1190 · Exploit Public-Facing Application T1499.003 · Application Exhaustion Flood
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I. Basic Information for CVE-2026-121727
Vulnerability Information
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Vulnerability Title
Kore before 4.3.0 Integer Underflow Memory Exhaustion via http_header_recv()
Source: CVE Program / CVE List V5
Vulnerability Description
Kore before 4.3.0 contains an integer underflow vulnerability in HTTP request body handling that allows unauthenticated attackers to bypass http_body_max by sending more body bytes than declared. Attackers can send oversized first segments over many concurrent POST, PUT or DELETE connections, wrapping content_length to grow buffers unbounded and exhaust worker memory.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
整数下溢(超界折返)
Source: CVE Program / CVE List V5
Affected Products
II. Public POCs for CVE-2026-121727
| # | POC Description | Source Link | Shenlong Link |
|---|
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Other References for CVE-2026-121727 (5)
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https://github.com/jorisvink/kore/blob/4.3.0-rc5/src/http.c#L934 technical-description
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https://kore.io/releases/4.3.0 release-notes
IV. Related Vulnerabilities
Same weakness: CWE-191