CVE-2026-55614

uhttpd vulnerable to HTTP request smuggling via case-sensitive Transfer-Encoding matching

State
Published
Severity
6.9 Medium
Published
Oct 30, 2026
Updated
Oct 30, 2026
Reserved
Jun 16, 2026

Read the record on cve.org

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.

Scores

CVSSScoreVectorSource
4.06.9 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:NGitHub_M

Weaknesses

  • CWE-444 Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

Affected Products

ProductVersions
uhttpdopenwrt
  • >= 2bef561c890f275ce3b785e6abdb3eda28c96aa8, < ae015e099986ceace44975cb69629841a2d58d37Affected
  • >= 2bef561c890f275ce3b785e6abdb3eda28c96aa8, < 6641b050e5f7c7fd9ae92e8e119d6d6dfc6e9837Affected

References

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