CVE-2026-31842

Tinyproxy HTTP request parsing desynchronization via case-sensitive Transfer-Encoding handling

Published Apr 7, 2026 CVSS 4.0 · 8.7 High EPSS < 1% KEV · Not listed
Description
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

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History
Type Values Removed Values Added
Description 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. 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.
Title Tinyproxy - HTTP Request Parsing Desynchronization via Case-Sensitive Transfer-Encoding Handling Tinyproxy HTTP request parsing desynchronization via case-sensitive Transfer-Encoding handling
Type Values Removed Values Added
Title Tinyproxy HTTP request parsing desynchronization via case-sensitive Transfer-Encoding handling Tinyproxy - HTTP Request Parsing Desynchronization via Case-Sensitive Transfer-Encoding Handling
Type Values Removed Values Added
CPEs cpe:2.3:a:tinyproxy_project:tinyproxy:*:*:*:*:*:*:*:*
Type Values Removed Values Added
First Time appeared Tinyproxy Project
Tinyproxy Project tinyproxy
Vendors & Products Tinyproxy Project
Tinyproxy Project tinyproxy
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description 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.
Title Tinyproxy HTTP request parsing desynchronization via case-sensitive Transfer-Encoding handling
Weaknesses CWE-444
References
Metrics cvssV2_0

{'score': 7.8, 'vector': 'AV:N/AC:L/Au:N/C:N/I:N/A:C'}

cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

cvssV4_0

{'score': 8.7, 'vector': '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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
TuranSec
Published
Updated
Aug 10, 2026, 11:43 AM
Reserved
Mar 9, 2026, 6:20 PM
Status
Modified
Published
Apr 7, 2026, 12:16 PM
Modified
Aug 10, 2026, 12:17 PM