CVE-2026-97399: One-byte overread in strncasecmp on Power8
The strncasecmp function in the GNU C Library 2.24 and later optimized for the Power8 architecture may read one byte beyond the input size limit, which may crash a program when that byte is not readable.
This condition may happen when the input strings to the strncasecmp function are attacker controlled in an application and they match all the way up to the edge of their page and the neighbouring page is either not mapped or is not readable.
Affected Software
Event History
Frequently Asked Questions
Which systems are exposed to this condition?
Systems using GNU C Library 2.24 or later on the Power8 architecture may be exposed. The issue is specific to the Power8-optimized implementation of strncasecmp.
What conditions are required to trigger a crash?
An application must call strncasecmp with attacker-controlled input strings that match through the end of a memory page. The following byte must be in an unmapped or unreadable neighboring page, so the one-byte read causes a fault.
What is the expected impact?
The described impact is a program crash when the out-of-bounds byte is unreadable. No confidentiality or integrity impact is identified in the provided severity vector.