CVE-2026-55614

Description

uhttpd is a small HTTP server. In unpatched repository snapshots, `client_parse_header()` in `client.c` lowercases header names but compares the `Transfer-Encoding` value to `chunked` using case-sensitive `strcmp`. A mixed-case transfer-coding token is accepted without enabling `r->transfer_chunked`, despite transfer-coding tokens being case-insensitive. On a keep-alive connection, the `chunked` POST body is left unread and request-shaped body bytes are parsed as another HTTP request, permitting HTTP request smuggling and boundary desynchronization. Commits ae015e099986ceace44975cb69629841a2d58d37 and 6641b050e5f7c7fd9ae92e8e119d6d6dfc6e9837 patch the issue.

References

https://github.com/tc4dy/CVE-2026-53921-PoC-Exploit

https://github.com/openwrt/uhttpd/security/advisories/GHSA-mcfg-c4r7-pjpf

https://github.com/openwrt/uhttpd/commit/ae015e099986ceace44975cb69629841a2d58d37

https://github.com/openwrt/uhttpd/commit/6641b050e5f7c7fd9ae92e8e119d6d6dfc6e9837

https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-114562

Details

Source: Mitre, NVD

Risk Information

CVSS v2

CVSS v3

CVSS v4

EPSS