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CVE-2026-55613— uhttpd: HTTP request smuggling via ubus POST body parse-error desync

Quick assessment

Affected
openwrt uhttpd
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.

uhttpd 是一款轻量级 HTTP 服务器。在未修复的代码库快照中， 文件中的 函数在 请求的 JSON 主体分多个 TCP 段到达时，会导致 HTTP 请求边界不同步。具体而言，首个完成 JSON 对象解析的段会设置 ；而后续到达的段则会进入“现有对象解析错误”处理路径，并返回“已消耗 0 字节”。调用方既未读取剩余的声明 所对应的数据，也未设置 标志。因此，嵌入在未被读取的响应体尾部中的 HTTP 请求，会被错误地当作同一持久连接（keep-alive）上的新请求进行处理。据报告，复现该漏洞的测试用例会先返回

CVSS 6.9 · Medium

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2026-55613

Vulnerability Information
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Vulnerability Title
uhttpd: HTTP request smuggling via ubus POST body parse-error desync
Source: CVE Program / CVE List V5
Vulnerability Description
uhttpd is a small HTTP server. In unpatched repository snapshots, `uh_ubus_data_send()` in `ubus.c` can desynchronize HTTP request boundaries when a `POST /ubus` JSON body arrives in multiple TCP segments. An initial segment completing a JSON object sets `du->jsobj`; a later segment takes the existing-object parse-error path and returns zero bytes consumed. The caller neither drains the remaining declared `Content-Length` nor sets `connection_close`. An HTTP request embedded in the unread body suffix is consequently processed as a new request on the same keep-alive connection. The reported reproducer returned a JSON-RPC parse error followed by a second HTTP response. This application-layer body-handler flaw is distinct from Transfer-Encoding header case handling and chunk-length state reset, and affects deployments enabling ubus, including the default OpenWrt configuration and potential proxy/CDN deployments. Repository patches 7b1bec45826bd78c8afc993435bdc0f1df2fe399 and b2285de129b9adc8b12f84f9a27c16c21f2b57a5 address this issue.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
HTTP请求的解释不一致性(HTTP请求私运)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
openwrt uhttpd < 7b1bec45826bd78c8afc993435bdc0f1df2fe399 -

II. Public POCs for CVE-2026-55613

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III. Intelligence Information for CVE-2026-55613

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Patches & Fixes for CVE-2026-55613 (2)

Vendor Advisories for CVE-2026-55613 (1)

Same Patch Batch · openwrt · 2026-10-30 · 3 CVEs total

CVE-2026-55614 6.9 MEDIUM uhttpd vulnerable to HTTP request smuggling via case-sensitive Transfer-Encoding matching
CVE-2026-55612 3.7 LOW uhttpd vulnerable to HTTP request smuggling via invalid chunk-length state reset

IV. Related Vulnerabilities

Same product: uhttpd
Same vendor: openwrt
Same weakness: CWE-444