PT-2026-30811 · Tinyproxy · Tinyproxy

Muxammadiyev Giyosiddin · Published 2026-04-07 · Updated 2026-04-07 · CVE-2026-31842

Mitre

CVSS v2.0

7.8

High

AV:N/AC:L/Au:N/C:N/I:N/A:C

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.

Fix

HTTP Request/Response Smuggling

Weakness Enumeration

CWE-444

Related Identifiers

CVE-2026-31842

Affected Products

Tinyproxy

References · 4

• https://nvd.nist.gov/vuln/detail/CVE-2026-31842 · Security Note
• https://github.com/tinyproxy/tinyproxy · Note
• https://github.com/tinyproxy/tinyproxy/issues/604 · Note
• https://datatracker.ietf.org/doc/html/rfc7230 · Note