CVE-2026-31842

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.

How to fix CVE-2026-31842

No fixed version has been published yet. Mitigate by removing the affected package or applying upstream guidance from the references below.

• —no fix listed

Is CVE-2026-31842 being exploited?

Low — EPSS is 0.1%, meaning exploitation activity has not been observed at scale.

Affected packages (1)

• from 0

CVSS scores

References (1)

• ADVISORYsecurity-tracker.debian.org/tracker/CVE-2026-31842