Executive brief
relibc is a standard C library used by the Redox operating system to handle core system functions like time and date processing. A flaw in how the library handles specific text characters can cause a program to crash unexpectedly when processing specially formatted dates. This could allow a local user to disrupt services or cause applications to stop working, leading to a denial of service.
Technical details
A vulnerability exists in relibc's implementation of strptime.rs (specifically within parse_month and parse_weekday) due to improper handling of UTF-8 character boundaries during string slicing. When the library attempts to slice a string based on the length of expected month or weekday names, it may attempt to slice in the middle of a multibyte character, triggering a Rust runtime panic. An attacker can exploit this by passing a crafted multibyte string to the strptime() function, leading to an immediate application crash (Denial of Service). The issue was identified in commit ab6a2e7 and addressed in merge request 990.
Affected products
- Redox OS relibc commit ab6a2e73223c9ff30cbbf5069d6758afb4cf08e3
Timeline
- 2026-02-10: patched: Merge request 990 submitted to fix the issue.
- 2026-06-26: advisory: CVE-2026-38639 published.