Executive brief
A security vulnerability exists in the Shibby Tomato router firmware, specifically within the component that manages Uninterruptible Power Supply (UPS) services. By sending a specially crafted response from a UPS device or a simulated UPS service, an attacker can cause the router's management interface to crash or potentially execute unauthorized commands. This could lead to a complete takeover of the router or a disruption of network services. Users should be aware that this software is no longer supported and has been replaced by the FreshTomato project.
Technical details
A stack-based buffer overflow exists in the 'tomatoups.cgi' component of Shibby Tomato firmware (up to version 1.28). The vulnerability is located in function 'sub_9068', which parses text protocol fields from a UPS service over TCP port 3551. The root cause is a failure to enforce length limits when using 'sscanf' with the '%s' format specifier and during byte-by-byte copy operations. Specifically, when handling the 'upstemp' field, an attacker-controlled UPS response exceeding 64 bytes can overwrite the stack, leading to memory corruption and potential remote code execution. This has been verified via dynamic analysis in QEMU. As the project is superseded by FreshTomato and no longer supported, no official patch is expected.
Affected products
- Shibby Tomato by Shibby up to 1.28
Timeline
- 2026-05-02: disclosed: Initial vulnerability report by Fengyi Wang
- 2026-05-29: advisory: CVE-2026-10066 published by VulDB/NVD