关键信息 Environment Build System: Make Operating System: Linux Operating System Version: Ubuntu 20.04 Hosted Environment: None libcoap Configuration Summary libcoap package version: 4.3.5 Operating System: x86_64-pc-linux-gnu OpenSSL version: 3.0.18-dev Problem Description Issue: Null pointer dereference in caused by improper handling of OpenSSL return values during certificate validation. Expected Behavior libcoap should detect the return value from and handle it appropriately. Actual Behavior When returns , libcoap attempts to access the type member of the null pointer, causing a segmentation fault. ASAN Log Resolution The issue was fixed with pull request #1750. The fix was confirmed to resolve the problem by the original reporter.