{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-31842","assignerOrgId":"309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c","state":"PUBLISHED","assignerShortName":"TuranSec","dateReserved":"2026-03-09T18:20:23.398Z","datePublished":"2026-04-07T11:17:33.621Z","dateUpdated":"2026-04-07T16:30:44.774Z"},"containers":{"cna":{"providerMetadata":{"orgId":"309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c","shortName":"TuranSec","dateUpdated":"2026-04-07T11:17:33.621Z"},"title":"Tinyproxy HTTP request parsing desynchronization via case-sensitive Transfer-Encoding handling","problemTypes":[{"descriptions":[{"lang":"en","cweId":"CWE-444","description":"CWE-444 Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')","type":"CWE"}]}],"impacts":[{"descriptions":[{"lang":"en","value":"An unauthenticated remote attacker can trigger HTTP request parsing desynchronization using a mixed-case Transfer-Encoding header (e.g., 'Chunked'), leading to backend connection hangs and denial of service. In certain deployments, request-body inspection and filtering mechanisms relying on Tinyproxy may also be bypassed."}]}],"affected":[{"vendor":"Tinyproxy Project","product":"Tinyproxy","platforms":["all"],"collectionURL":"https://github.com/tinyproxy/tinyproxy","versions":[{"status":"affected","version":"0","lessThanOrEqual":"1.11.3","versionType":"custom"}],"defaultStatus":"unaffected"}],"descriptions":[{"lang":"en","value":"Tinyproxy through 1.11.3 is vulnerable to HTTP request parsing desynchronization due to a case-sensitive comparison of the Transfer-Encoding header in src/reqs.c. The is_chunked_transfer() function uses strcmp() to compare the header value against \"chunked\", even though RFC 7230 specifies that transfer-coding names are case-insensitive. By sending a request with Transfer-Encoding: Chunked, an unauthenticated remote attacker can cause Tinyproxy to misinterpret the request as having no body. In this state, Tinyproxy sets content_length.client to -1, skips pull_client_data_chunked(), forwards request headers upstream, and transitions into relay_connection() raw TCP forwarding while unread body data remains buffered. This leads to inconsistent request state between Tinyproxy and backend servers. RFC-compliant backends (e.g., Node.js, Nginx) will continue waiting for chunked body data, causing connections to hang indefinitely. This behavior enables application-level denial of service through backend worker exhaustion. Additionally, in deployments where Tinyproxy is used for request-body inspection, filtering, or security enforcement, the unread body may be forwarded without proper inspection, resulting in potential security control bypass.","supportingMedia":[{"type":"text/html","base64":false,"value":"<p>Tinyproxy through 1.11.3 is vulnerable to HTTP request parsing desynchronization due to a case-sensitive comparison of the Transfer-Encoding header in src/reqs.c. The is_chunked_transfer() function uses strcmp() to compare the header value against \"chunked\", even though RFC 7230 specifies that transfer-coding names are case-insensitive. By sending a request with Transfer-Encoding: Chunked, an unauthenticated remote attacker can cause Tinyproxy to misinterpret the request as having no body. In this state, Tinyproxy sets content_length.client to -1, skips pull_client_data_chunked(), forwards request headers upstream, and transitions into relay_connection() raw TCP forwarding while unread body data remains buffered. This leads to inconsistent request state between Tinyproxy and backend servers. RFC-compliant backends (e.g., Node.js, Nginx) will continue waiting for chunked body data, causing connections to hang indefinitely. This behavior enables application-level denial of service through backend worker exhaustion. Additionally, in deployments where Tinyproxy is used for request-body inspection, filtering, or security enforcement, the unread body may be forwarded without proper inspection, resulting in potential security control bypass.</p>"}]}],"references":[{"url":"https://github.com/tinyproxy/tinyproxy/issues/604","name":"Upstream issue report and reproduction details","tags":["issue-tracking","technical-description","third-party-advisory"]},{"url":"https://github.com/tinyproxy/tinyproxy","name":"Tinyproxy upstream project","tags":["product"]},{"url":"https://datatracker.ietf.org/doc/html/rfc7230","name":"RFC 7230: transfer-coding names are case-insensitive","tags":["technical-description"]}],"metrics":[{"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}],"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","subConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","subIntegrityImpact":"NONE","vulnAvailabilityImpact":"HIGH","subAvailabilityImpact":"NONE","exploitMaturity":"NOT_DEFINED","Safety":"NOT_DEFINED","Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","valueDensity":"NOT_DEFINED","vulnerabilityResponseEffort":"NOT_DEFINED","providerUrgency":"NOT_DEFINED","version":"4.0","baseSeverity":"HIGH","baseScore":8.7,"vectorString":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"}},{"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}],"cvssV3_1":{"version":"3.1","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH","baseSeverity":"HIGH","baseScore":7.5,"vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}},{"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}],"cvssV2_0":{"version":"2.0","accessVector":"NETWORK","accessComplexity":"LOW","authentication":"NONE","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"COMPLETE","baseScore":7.8,"vectorString":"AV:N/AC:L/Au:N/C:N/I:N/A:C"}}],"credits":[{"lang":"en","value":"Muxammadiyev G'iyosiddin","type":"finder"}],"source":{"discovery":"EXTERNAL"},"x_generator":{"engine":"Vulnogram 1.0.1"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-04-07T16:30:26.482367Z","id":"CVE-2026-31842","options":[{"Exploitation":"poc"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-04-07T16:30:44.774Z"}}]}}