Medium (5.9) in botan project botan. EPSS 0.5% chance of exploitation in the next 30 days.
Botan before 3.6.0, when certain GCC versions are used, has a compiler-induced secret-dependent operation in lib/utils/donna128.h in donna128 (used in Chacha-Poly1305 and x25519). An addition can be skipped if a carry is not set. This was observed for GCC 11.3.0 with -O2 on MIPS, and GCC on x86-i386. (Only 32-bit processors can be affected.)
Severity
CVSS 3.1
5.9 medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
EPSS
0.5% chance of exploitation in the next 30 days; higher than 45% of CVEs (scores of 2026-10-31)