# DF-0305 -- Low

## Verdict: REPRODUCED (source-confirmed)

REAL: carp_hmac_verify uses bcmp(md, md2, sizeof(md2)) which may short-circuit on the first differing byte -> timing oracle for byte-by-byte HMAC brute force (network jitter makes remote impractical, but violates crypto constant-time standards).

## Impact ceiling
none

## Cited refs
- sys/netinet/ip_carp.c:581

## Fix
Replace bcmp with a constant-time XOR-accumulation compare.

## Validation
Combined 60-finding fix kernel (findings/poc/_low_merged.patch) built `make -j6 nativekernel KERNCONF=X86_64_GENERIC` => rc=0, 0 errors, -Werror. fix_status=fixed.