{ "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": "

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.

" } ] } ], "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" } } ] } }