CVE-2026-55613

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CVE-2026-55613

Summary: uhttpd: HTTP request smuggling via ubus POST body parse-error desync

Details: 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.

References: https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55613.json, https://github.com/openwrt/uhttpd/security/advisories/GHSA-wgwp-64hh-f52p, https://nvd.nist.gov/vuln/detail/CVE-2026-55613, https://github.com/openwrt/uhttpd/commit/7b1bec45826bd78c8afc993435bdc0f1df2fe399, https://github.com/openwrt/uhttpd/commit/b2285de129b9adc8b12f84f9a27c16c21f2b57a5