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CVE-2026-55614

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

6.9 Medium

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
Low
Availability
None

Exploit likelihood

0.40%Unchanged since Oct 31, 2026
90%50%10%1%

What each source reports

CVE List Score used 6.9

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

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.

Record
CVE-2026-55614
CVSS 4.0
6.9 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
Weakness
CWE-444
Updated
2026-11-02
EUVDEUVD-2026-114562 6.9

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.

Record
EUVD-2026-114562
CVSS 4.0
6.9 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
Updated
2026-11-06
NVD 6.9

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.

Record
CVE-2026-55614
CVSS 4.0
6.9 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Weakness
CWE-444
Updated
2026-11-03
OSV 6.9

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

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.

Record
CVE-2026-55614
CVSS 4.0
6.9 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
Weakness
CWE-444
Updated
2026-11-04

Affected products

History

History
RecordedChangedSources
factsNVD, OSV
first indexedCVE List, EUVD, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-55614 is a medium vulnerability (CVSS 6.9) in Openwrt Uhttpd, published October 30, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.40%, the 33rd percentile. No source names a fixed version.

References

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