Description

An integer overflow vulnerability in the HTTP chunked transfer encoding parser in tinyproxy up to and including version 1.11.3 allows an unauthenticated remote attacker to cause a denial of service (DoS). The issue occurs because chunk size values are parsed using strtol() without properly validating overflow conditions (e.g., errno == ERANGE). A crafted chunk size such as 0x7fffffffffffffff (LONG_MAX) bypasses the existing validation check (chunklen < 0), leading to a signed integer overflow during arithmetic operations (chunklen + 2). This results in incorrect size calculations, causing the proxy to attempt reading an extremely large amount of request-body data and holding worker connections open indefinitely. An attacker can exploit this behavior to exhaust all available worker slots, preventing new connections from being accepted and causing complete service unavailability. Upstream addressed this issue in commit bb7edc4; however, the latest stable release (1.11.3) remains affected at the time of publication.

Weaknesses 1

References 5

• github.com https://github.com/tinyproxy/tinyproxy/commit/969852c
• github.com https://github.com/tinyproxy/tinyproxy/commit/bb7edc4
• github.com https://github.com/tinyproxy/tinyproxy/issues/602
• github.com https://github.com/tinyproxy/tinyproxy/pull/603
• github.com https://github.com/tinyproxy/tinyproxy/releases

Remediation