wolfSSL ML-KEM ARM64 NEON Incomplete Ciphertext Comparison Breaks Fujisaki-Okamoto Implicit Rejection

#!/usr/bin/env bash
# CVE-2026-6330 Detection Script
# Checks for vulnerable wolfSSL ML-KEM NEON codepath
# Output: VULNERABLE / PATCHED / UNKNOWN
# Exit codes: 2=VULNERABLE, 0=PATCHED, 1=UNKNOWN

set -euo pipefail

RESULT="UNKNOWN"
ARCH=$(uname -m 2>/dev/null || echo "unknown")

# Locate wolfSSL library
WOLFSSL_LIB=""
for candidate in \
  /usr/lib/libwolfssl.so \
  /usr/local/lib/libwolfssl.so \
  /usr/lib/aarch64-linux-gnu/libwolfssl.so \
  /usr/lib64/libwolfssl.so \
  /opt/wolfssl/lib/libwolfssl.so; do
  if [ -f "$candidate" ]; then
    WOLFSSL_LIB="$candidate"
    break
  fi
done

# Also check pkg-config
if [ -z "$WOLFSSL_LIB" ] && command -v pkg-config &>/dev/null; then
  WOLFSSL_LIB=$(pkg-config --variable=libdir wolfssl 2>/dev/null || true)
  if [ -n "$WOLFSSL_LIB" ]; then
    WOLFSSL_LIB="${WOLFSSL_LIB}/libwolfssl.so"
    [ ! -f "$WOLFSSL_LIB" ] && WOLFSSL_LIB=""
  fi
fi

if [ -z "$WOLFSSL_LIB" ]; then
  echo "[INFO] wolfSSL library not found on this host."
  echo "UNKNOWN"
  exit 1
fi

echo "[INFO] Found wolfSSL at: $WOLFSSL_LIB"

# Extract version string from library
VERSION=$(strings "$WOLFSSL_LIB" 2>/dev/null | grep -oP 'wolfSSL \K[0-9]+\.[0-9]+\.[0-9]+' | head -1 || true)

if [ -z "$VERSION" ]; then
  # Try wolfssl-config
  if command -v wolfssl-config &>/dev/null; then
    VERSION=$(wolfssl-config --version 2>/dev/null || true)
  fi
fi

if [ -z "$VERSION" ]; then
  echo "[WARN] Could not determine wolfSSL version."
  echo "UNKNOWN"
  exit 1
fi

echo "[INFO] wolfSSL version: $VERSION"
echo "[INFO] Architecture: $ARCH"

# Parse version components
IFS='.' read -r MAJOR MINOR PATCH <<< "$VERSION"

# Check if ARM64/aarch64
IS_ARM64=false
if [[ "$ARCH" == "aarch64" || "$ARCH" == "arm64" ]]; then
  IS_ARM64=true
fi

# Check NEON symbols in library
HAS_NEON=false
if $IS_ARM64 && strings "$WOLFSSL_LIB" 2>/dev/null | grep -qi 'neon\|mlkem.*neon\|kyber.*neon'; then
  HAS_NEON=true
fi

# Version comparison: vulnerable is 5.7.4 <= version <= 5.9.1
is_vulnerable_version() {
  if [ "$MAJOR" -lt 5 ]; then return 1; fi
  if [ "$MAJOR" -gt 5 ]; then return 1; fi
  # MAJOR is 5
  if [ "$MINOR" -lt 7 ]; then return 1; fi
  if [ "$MINOR" -eq 7 ] && [ "$PATCH" -lt 4 ]; then return 1; fi
  if [ "$MINOR" -gt 9 ]; then return 1; fi
  if [ "$MINOR" -eq 9 ] && [ "$PATCH" -ge 2 ]; then return 1; fi
  return 0
}

if is_vulnerable_version; then
  if $IS_ARM64; then
    echo "[ALERT] wolfSSL $VERSION on ARM64 — NEON ML-KEM codepath is vulnerable to CVE-2026-6330."
    RESULT="VULNERABLE"
  else
    echo "[INFO] wolfSSL $VERSION is in the vulnerable range but this host is $ARCH (not ARM64)."
    echo "[INFO] CVE-2026-6330 (NEON) does not apply. Check CVE-2026-10097 (AVX2) if x86_64."
    RESULT="PATCHED"
  fi
else
  echo "[INFO] wolfSSL $VERSION is outside the vulnerable range (5.7.4–5.9.1)."
  RESULT="PATCHED"
fi

echo "$RESULT"
case "$RESULT" in
  VULNERABLE) exit 2 ;;
  PATCHED)    exit 0 ;;
  *)          exit 1 ;;
esac