Executive brief
tinyproxy is a lightweight HTTP proxy server used to forward and cache web traffic in corporate networks and embedded systems. An integer overflow flaw in its HTTP request parser allows a remote attacker to crash the proxy service by sending specially crafted HTTP requests, causing denial of service and disrupting network connectivity for downstream clients.
Technical details
The vulnerability is an integer overflow in the HTTP chunked transfer encoding parser (pull_client_data_chunked function in src/reqs.c). The chunk size is parsed using strtol() without validating overflow conditions (errno == ERANGE) or negative values. An unauthenticated remote attacker can send a malicious HTTP request with a crafted chunked transfer encoding header to trigger integer overflow, leading to memory corruption or process termination. The vulnerability requires network access to the proxy port but no authentication. Patches were released in commits 969852c (negative value check) and bb7edc4 (overflow prevention) to validate chunk length values before processing.
Affected products
- tinyproxy tinyproxy up to and including 1.11.3
Timeline
- 2026-03-30: disclosed
- 2026: patched: Fixed in commits 969852c and bb7edc4