diff --git a/src/client/client.c b/src/client/client.c
index 61fcf117..46c3ce75 100644
--- a/src/client/client.c
+++ b/src/client/client.c
@@ -34,6 +34,8 @@
 #endif
 #include <wolfssl/wolfcrypt/settings.h>
 
+#include <ctype.h>
+
 #include <wolfssl/ssl.h>
 
 #include <wolfclu/clu_header_main.h>
@@ -147,6 +149,17 @@ static WC_INLINE void clu_build_addr(SOCKADDR_IN4_T* addr, SOCKADDR_IN6_T* ipv6,
                 FILE* fp;
                 char host_out[100];
                 char cmd[100];
+                const char* cp;
+
+                /* Validate hostname: only allow characters valid in DNS names
+                 * (RFC 1123) to prevent shell injection via popen(). */
+                for (cp = peer; *cp != '\0'; cp++) {
+                    if (!isalnum((unsigned char)*cp) &&
+                            *cp != '.' && *cp != '-') {
+                        err_sys("invalid character in hostname");
+                        return;
+                    }
+                }
 
                 XSTRNCPY(cmd, "host ", 6);
                 XSTRNCAT(cmd, peer, 99 - XSTRLEN(cmd));
diff --git a/src/x509/clu_x509_sign.c b/src/x509/clu_x509_sign.c
index 7d5625cd..ab409042 100644
--- a/src/x509/clu_x509_sign.c
+++ b/src/x509/clu_x509_sign.c
@@ -257,7 +257,7 @@ int wolfCLU_GenChimeraCertSign(WOLFSSL_BIO *bioCaKey, WOLFSSL_BIO *bioAltCaKey,
     const char *altSigAlgOid        = "2.5.29.73";
     const char *altSigValOid        = "2.5.29.74";
 
-    /* 
+    /*
      * LARGE_TEMO_SZ defines the size of temporary buffers used for signature key,
      * verification key and signature value buffers.
      * The value 11264 is enough for P-521 and ML-DSA-87 PEM certs.
@@ -397,7 +397,7 @@ int wolfCLU_GenChimeraCertSign(WOLFSSL_BIO *bioCaKey, WOLFSSL_BIO *bioAltCaKey,
                 ret = WOLFCLU_FATAL_ERROR;
             }
         }
-        
+
         if (ret == 0) {
             XMEMSET(caKeyBuf, 0, caKeySz); /* clear original buffer */
             caKeySz = derObj->length;
@@ -667,13 +667,13 @@ int wolfCLU_GenChimeraCertSign(WOLFSSL_BIO *bioCaKey, WOLFSSL_BIO *bioAltCaKey,
 
     if (ret == WOLFCLU_SUCCESS) {
         switch (level) {
-            case 2: 
+            case 2:
                 newCert.sigType = CTC_SHA256wECDSA;
                 break;
-            case 3: 
+            case 3:
                 newCert.sigType = CTC_SHA384wECDSA;
                 break;
-            case 5: 
+            case 5:
                 newCert.sigType = CTC_SHA512wECDSA;
                 break;
         }
@@ -691,7 +691,7 @@ int wolfCLU_GenChimeraCertSign(WOLFSSL_BIO *bioCaKey, WOLFSSL_BIO *bioAltCaKey,
             else {
                 ret = WOLFCLU_SUCCESS;
             }
-        }        
+        }
     }
 
     if (ret == WOLFCLU_SUCCESS) {
@@ -715,7 +715,7 @@ int wolfCLU_GenChimeraCertSign(WOLFSSL_BIO *bioCaKey, WOLFSSL_BIO *bioAltCaKey,
     }
 
     if (ret == WOLFCLU_SUCCESS && isCA) {
-        ret = wc_MakeCert(&newCert, scratchBuf, 
+        ret = wc_MakeCert(&newCert, scratchBuf,
                             scratchSz, NULL, &caKey, &rng);
         if (ret <= 0) {
             wolfCLU_LogError("Error making certificate");
@@ -732,7 +732,7 @@ int wolfCLU_GenChimeraCertSign(WOLFSSL_BIO *bioCaKey, WOLFSSL_BIO *bioAltCaKey,
                 scratchSz = ret;
                 ret = WOLFCLU_SUCCESS;
             }
-        }        
+        }
     }
     else if (ret == WOLFCLU_SUCCESS && !isCA) {
         ret = wc_MakeCert(&newCert, scratchBuf, scratchSz,
@@ -1274,7 +1274,13 @@ int wolfCLU_CertSign(WOLFCLU_CERT_SIGN* csign, WOLFSSL_X509* x509)
             case WC_HASH_TYPE_BLAKE2B:
             case WC_HASH_TYPE_BLAKE2S:
 
-    #if LIBWOLFSSL_VERSION_HEX > 0x05001000
+    #if LIBWOLFSSL_VERSION_HEX >= 0x05009000
+            case WC_HASH_TYPE_SHA512_224:
+            case WC_HASH_TYPE_SHA512_256:
+            case WC_HASH_TYPE_SHAKE128:
+            case WC_HASH_TYPE_SHAKE256:
+            case WC_HASH_TYPE_SM3:
+    #elif LIBWOLFSSL_VERSION_HEX > 0x05001000
         #ifndef WOLFSSL_NOSHA512_224
             case WC_HASH_TYPE_SHA512_224:
         #endif
diff --git a/tests/client/client-test.sh b/tests/client/client-test.sh
index 88297c2d..00e6a329 100755
--- a/tests/client/client-test.sh
+++ b/tests/client/client-test.sh
@@ -25,5 +25,39 @@ fi
 
 rm tmp.crt
 
+# Regression tests: shell injection via hostname must not execute injected command.
+# Applies to the WOLFSSL_USE_POPEN_HOST path where peer is concatenated into a
+# popen() shell command.  On other builds, getaddrinfo/gethostbyname reject
+# these hostnames before any shell is involved, so the tests pass either way.
+INJFILE="clu_injection_probe.txt"
+rm -f "$INJFILE"
+
+# Semicolon: "evil.com;touch clu_injection_probe.txt" passed as peer
+./wolfssl s_client -connect 'evil.com;touch clu_injection_probe.txt:443' \
+    2>/dev/null
+if [ -f "$INJFILE" ]; then
+    echo "SECURITY FAILURE: command injection via hostname (semicolon)"
+    rm -f "$INJFILE"
+    exit 99
+fi
+
+# Command substitution: "$(touch clu_injection_probe.txt)" passed as peer
+./wolfssl s_client -connect 'evil$(touch clu_injection_probe.txt).com:443' \
+    2>/dev/null
+if [ -f "$INJFILE" ]; then
+    echo "SECURITY FAILURE: command injection via hostname (command substitution)"
+    rm -f "$INJFILE"
+    exit 99
+fi
+
+# Pipe: "evil.com|touch clu_injection_probe.txt" passed as peer
+./wolfssl s_client -connect 'evil.com|touch clu_injection_probe.txt:443' \
+    2>/dev/null
+if [ -f "$INJFILE" ]; then
+    echo "SECURITY FAILURE: command injection via hostname (pipe)"
+    rm -f "$INJFILE"
+    exit 99
+fi
+
 echo "Done"
 exit 0
diff --git a/tests/ocsp/ocsp-interop-test.sh b/tests/ocsp/ocsp-interop-test.sh
index 49c8a75a..2ceda899 100755
--- a/tests/ocsp/ocsp-interop-test.sh
+++ b/tests/ocsp/ocsp-interop-test.sh
@@ -293,7 +293,7 @@ if [ $RESULT = 0 ]; then
 fi
 
 # Check for error message
-grep -qi "fail\|error\|not found\|unable" "$TEST_DIR/test6.log"
+grep -qi "fail\|error\|not found\|unable\|no such\|could not" "$TEST_DIR/test6.log"
 if [ $? != 0 ]; then
     echo "Test 6 failed: expected error message about invalid file"
     exit 99