diff --git a/lib/creds.c b/lib/creds.c
index a11816ca54..b24b8af24c 100644
--- a/lib/creds.c
+++ b/lib/creds.c
@@ -46,6 +46,7 @@ CURLcode Curl_creds_create(const char *user,
   size_t salen = sasl_authzid ? strlen(sasl_authzid) : 0;
   size_t sslen = sasl_service ? strlen(sasl_service) : 0;
   char *s, *buf;
+  size_t bufsize;
   CURLcode result = CURLE_OK;
 
   Curl_creds_unlink(pcreds);
@@ -64,13 +65,14 @@ CURLcode Curl_creds_create(const char *user,
   }
 
   /* null-terminator for user already part of struct */
-  creds = curlx_calloc(1, sizeof(*creds) +
-                       ulen + plen + 1 + olen + 1 + salen + 1 + sslen + 1);
+  bufsize = ulen + plen + 1 + olen + 1 + salen + 1 + sslen + 1;
+  creds = curlx_calloc(1, sizeof(*creds) + bufsize);
   if(!creds) {
     result = CURLE_OUT_OF_MEMORY;
     goto out;
   }
 
+  creds->bufsize = bufsize;
   creds->refcount = 1;
   creds->source = source;
   /* Some compilers try to be too smart about our dynamic struct size */
@@ -144,6 +146,7 @@ void Curl_creds_unlink(struct Curl_creds **pcreds)
     if(creds->refcount)
       creds->refcount--;
     if(!creds->refcount) {
+      curlx_memzero(creds, sizeof(*creds) + creds->bufsize);
       curlx_free(creds);
     }
   }
diff --git a/lib/creds.h b/lib/creds.h
index 36deff323e..8b14cad719 100644
--- a/lib/creds.h
+++ b/lib/creds.h
@@ -39,6 +39,7 @@ struct Curl_creds {
   const char *sasl_service; /* non-NULL, maybe empty string */
   uint32_t refcount;
   uint8_t source; /* CREDS_* value */
+  size_t bufsize; /* extra bytes added to sizeof(struct Curl_creds) */
   char buf[1];
 };
 
diff --git a/lib/curl_setup.h b/lib/curl_setup.h
index 0bbf717c89..bcad79beb9 100644
--- a/lib/curl_setup.h
+++ b/lib/curl_setup.h
@@ -1338,20 +1338,6 @@ extern curl_calloc_callback Curl_ccalloc;
     (ptr) = NULL;           \
   } while(0)
 
-/* Same as curlx_safefree() but zeroes memory before freeing */
-#define curlx_safefreezero(ptr, size) \
-  do {                                \
-    curlx_freezero(ptr, size);        \
-    (ptr) = NULL;                     \
-  } while(0)
-
-/* Same as curlx_safefreezero() but determines length with strlen() */
-#define curlx_safefreezeroz(ptr) \
-  do {                           \
-    curlx_freezeroz(ptr);        \
-    (ptr) = NULL;                \
-  } while(0)
-
 #include <curl/curl.h> /* for CURL_EXTERN, curl_socket_t, mprintf.h */
 
 #ifdef DEBUGBUILD
@@ -1642,14 +1628,14 @@ typedef struct sockaddr_un {
 #if defined(_MSC_VER) && defined(NTDDI_VERSION) && \
   (NTDDI_VERSION >= 0x0A000010) /* MS SDK 10.0.26100.0+ */
 #pragma comment(lib, "volatileaccessu.lib")
-#define curlx_memzero(buf, size)  SecureZeroMemory2(buf, size)
+#define curlx_memzero_low(buf, size)  SecureZeroMemory2(buf, size)
 #else
-#define curlx_memzero(buf, size)  SecureZeroMemory(buf, size)
+#define curlx_memzero_low(buf, size)  SecureZeroMemory(buf, size)
 #endif
 #elif defined(HAVE_MEMSET_S)
-#define curlx_memzero(buf, size)  (void)memset_s(buf, size, 0, size)
+#define curlx_memzero_low(buf, size)  (void)memset_s(buf, size, 0, size)
 #elif defined(HAVE_MEMSET_EXPLICIT)
-#define curlx_memzero(buf, size)  (void)memset_explicit(buf, 0, size)
+#define curlx_memzero_low(buf, size)  (void)memset_explicit(buf, 0, size)
 #elif defined(__CYGWIN__) || \
   (defined(__NEWLIB__) && !defined(__CLIB2__)) || \
   (defined(__GLIBC__) && \
@@ -1657,17 +1643,29 @@ typedef struct sockaddr_un {
   (defined(__DragonFly__) && __DragonFly_version >= 500600 /* v5.6+ */) || \
   (defined(__FreeBSD__) && __FreeBSD_version >= 1100037 /* v11.0+ */) || \
   (defined(__OpenBSD__) && OpenBSD >= 201405 /* v5.5+ */)
-#define curlx_memzero(buf, size)  explicit_bzero(buf, size)
+#define curlx_memzero_low(buf, size)  explicit_bzero(buf, size)
 #elif defined(__NetBSD__) && __NetBSD_Version__ >= 702000000 /* v7.2+ */
-#define curlx_memzero(buf, size)  (void)explicit_memset(buf, 0, size)
+#define curlx_memzero_low(buf, size)  (void)explicit_memset(buf, 0, size)
 #endif
 #endif /* !_CURL_LOCAL_MEMZERO */
 
-#ifndef curlx_memzero
+#ifndef curlx_memzero_low
 #define USE_CURLX_MEMZERO
-void curlx_memzero(void *buf, size_t size);
+void curlx_memzero_low(void *buf, size_t size);
 #endif
-void curlx_freezero(void *buf, size_t size);
-void curlx_freezeroz(void *buf);
+
+/* Public macro with NULL-check */
+#define curlx_memzero(ptr, size)    \
+  do {                              \
+    if(ptr)                         \
+      curlx_memzero_low(ptr, size); \
+  } while(0)
+
+/* Public macro with NULL-check for null-terminated strings */
+#define curlx_strzero(str)                 \
+  do {                                     \
+    if(str)                                \
+      curlx_memzero_low(str, strlen(str)); \
+  } while(0)
 
 #endif /* HEADER_CURL_SETUP_H */
diff --git a/lib/curl_share.c b/lib/curl_share.c
index 94469bc3ef..b7c331adf7 100644
--- a/lib/curl_share.c
+++ b/lib/curl_share.c
@@ -34,6 +34,9 @@
 
 static void share_destroy(struct Curl_share *share)
 {
+  if(!share)
+    return;
+
   if(share->specifier & (1 << CURL_LOCK_DATA_CONNECT)) {
     Curl_cpool_destroy(&share->cpool);
   }
@@ -61,7 +64,7 @@ static void share_destroy(struct Curl_share *share)
 #ifdef USE_MUTEX
   Curl_mutex_destroy(&share->lock);
 #endif
-  share->magic = 0;
+  curlx_memzero(share, sizeof(*share));
   curlx_free(share);
 }
 
diff --git a/lib/curl_sspi.c b/lib/curl_sspi.c
index 3ea17621b1..c733892d86 100644
--- a/lib/curl_sspi.c
+++ b/lib/curl_sspi.c
@@ -100,6 +100,7 @@ CURLcode Curl_create_sspi_identity(const char *userp, const char *passwdp,
   xcharp_u domain, dup_domain;
   xcharp_u passwd, dup_passwd;
   size_t domlen = 0;
+  size_t pwlen;
 
   domain.const_tchar_ptr = TEXT("");
 
@@ -155,17 +156,20 @@ CURLcode Curl_create_sspi_identity(const char *userp, const char *passwdp,
     curlx_free(dup_domain.tchar_ptr);
     return CURLE_OUT_OF_MEMORY;
   }
+  pwlen = _tcslen(passwd.tchar_ptr);
   dup_passwd.tchar_ptr = curlx_tcsdup(passwd.tchar_ptr);
   if(!dup_passwd.tchar_ptr) {
     curlx_free(dup_user.tchar_ptr);
     curlx_free(dup_domain.tchar_ptr);
+    curlx_memzero(passwd.tchar_ptr, pwlen * sizeof(*passwd.tchar_ptr));
     curlx_free(passwd.tchar_ptr);
     return CURLE_OUT_OF_MEMORY;
   }
   identity->Password = dup_passwd.tbyte_ptr;
-  identity->PasswordLength = curlx_uztoul(_tcslen(dup_passwd.tchar_ptr));
+  identity->PasswordLength = curlx_uztoul(pwlen);
   dup_passwd.tchar_ptr = NULL;
 
+  curlx_memzero(passwd.tchar_ptr, pwlen * sizeof(*passwd.tchar_ptr));
   curlx_free(passwd.tchar_ptr);
 
   identity->User = dup_user.tbyte_ptr;
@@ -199,6 +203,8 @@ void Curl_sspi_free_identity(SEC_WINNT_AUTH_IDENTITY *identity)
 {
   if(identity) {
     curlx_safefree(identity->User);
+    curlx_memzero(identity->Password,
+                  identity->PasswordLength * sizeof(*identity->Password));
     curlx_safefree(identity->Password);
     curlx_safefree(identity->Domain);
   }
diff --git a/lib/curlx/strdup.c b/lib/curlx/strdup.c
index 8e788ea34c..c4dd8f969d 100644
--- a/lib/curlx/strdup.c
+++ b/lib/curlx/strdup.c
@@ -101,25 +101,9 @@ static void *(* const volatile p_curlx_memset)(void *buf, int val,
 
 /* Local fallback in case there is no system function to securely zero a memory
    buffer. */
-void curlx_memzero(void *buf, size_t size)
+void curlx_memzero_low(void *buf, size_t size)
 {
   if(buf)
     p_curlx_memset(buf, 0, size);
 }
 #endif
-
-/* Free 'buf' after zeroing its content. */
-void curlx_freezero(void *buf, size_t size)
-{
-  if(buf)
-    curlx_memzero(buf, size);
-  curlx_free(buf);
-}
-
-/* Free 'buf' after zeroing its content, where 'buf' is null-terminated. */
-void curlx_freezeroz(void *buf)
-{
-  if(buf)
-    curlx_memzero(buf, strlen(buf));
-  curlx_free(buf);
-}
diff --git a/lib/imap.c b/lib/imap.c
index fc3077985d..5c1229193b 100644
--- a/lib/imap.c
+++ b/lib/imap.c
@@ -613,6 +613,7 @@ static CURLcode imap_perform_login(struct Curl_easy *data,
                       passwd ? passwd : "");
 
   curlx_free(user);
+  curlx_strzero(passwd);
   curlx_free(passwd);
 
   if(!result)
diff --git a/lib/mqtt.c b/lib/mqtt.c
index 8482477b97..87b94c0f75 100644
--- a/lib/mqtt.c
+++ b/lib/mqtt.c
@@ -347,8 +347,10 @@ static CURLcode mqtt_connect(struct Curl_easy *data)
     result = mqtt_send(data, packet, packetlen);
 
 end:
-  if(packet)
+  if(packet) {
+    curlx_memzero(packet, packetlen);
     curlx_free(packet);
+  }
   Curl_creds_unlink(&data->state.creds);
   return result;
 }
diff --git a/lib/multi.c b/lib/multi.c
index d0fa68ab4c..772116e9f5 100644
--- a/lib/multi.c
+++ b/lib/multi.c
@@ -3043,6 +3043,7 @@ CURLMcode curl_multi_cleanup(CURLM *m)
     Curl_uint32_bset_destroy(&multi->pending);
     Curl_uint32_bset_destroy(&multi->msgsent);
     Curl_uint32_tbl_destroy(&multi->xfers);
+    curlx_memzero(multi, sizeof(*multi));
     curlx_free(multi);
 
     return CURLM_OK;
diff --git a/lib/setopt.c b/lib/setopt.c
index e2e30622f1..6e366456c0 100644
--- a/lib/setopt.c
+++ b/lib/setopt.c
@@ -154,6 +154,7 @@ static CURLcode setstropt_userpwd(const char *option, char **userp,
   curlx_free(*userp);
   *userp = user;
 
+  curlx_strzero(*passwdp);
   curlx_free(*passwdp);
   *passwdp = passwd;
 
@@ -1657,6 +1658,7 @@ static CURLcode setopt_cptr_proxy(struct Curl_easy *data, CURLoption option,
       result = Curl_urldecode(p, 0, &s->str[STRING_PROXYPASSWORD], NULL,
                               REJECT_ZERO);
     curlx_free(u);
+    curlx_strzero(p);
     curlx_free(p);
     break;
   }
diff --git a/lib/url.c b/lib/url.c
index 8da2aca924..0ce9639c0e 100644
--- a/lib/url.c
+++ b/lib/url.c
@@ -153,6 +153,15 @@ void Curl_freeset(struct Curl_easy *data)
   enum dupblob j;
 
   for(i = (enum dupstring)0; i < STRING_LAST; i++) {
+    if(i == STRING_PASSWORD ||
+       i == STRING_KEY_PASSWD ||
+#ifndef CURL_DISABLE_PROXY
+       i == STRING_PROXYPASSWORD ||
+       i == STRING_KEY_PASSWD_PROXY ||
+#endif
+       i == STRING_BEARER) {
+      curlx_strzero(data->set.str[i]);
+    }
     curlx_safefree(data->set.str[i]);
   }
 
@@ -306,6 +315,7 @@ CURLcode Curl_close(struct Curl_easy **datap)
 #ifndef CURL_DISABLE_PROXY
   Curl_ssl_config_cleanup(&data->set.proxy_ssl.primary);
 #endif
+  curlx_memzero(data, sizeof(*data));
   curlx_free(data);
   return CURLE_OK;
 }
diff --git a/lib/urlapi.c b/lib/urlapi.c
index 7a926debb6..1739b21bcc 100644
--- a/lib/urlapi.c
+++ b/lib/urlapi.c
@@ -69,6 +69,7 @@ static void free_urlhandle(struct Curl_URL *u)
 {
   curlx_free(u->scheme);
   curlx_free(u->user);
+  curlx_strzero(u->password);
   curlx_free(u->password);
   curlx_free(u->options);
   curlx_free(u->host);
@@ -322,6 +323,7 @@ UNITTEST CURLUcode parse_hostname_login(struct Curl_URL *u,
   }
 
   if(passwdp) {
+    curlx_strzero(u->password);
     curlx_free(u->password);
     u->password = passwdp;
   }
@@ -338,6 +340,7 @@ UNITTEST CURLUcode parse_hostname_login(struct Curl_URL *u,
 out:
 
   curlx_free(userp);
+  curlx_strzero(passwdp);
   curlx_free(passwdp);
   curlx_free(optionsp);
   curlx_safefree(u->user);
@@ -1783,6 +1786,7 @@ static CURLUcode urlset_clear(CURLU *u, CURLUPart what)
     curlx_safefree(u->user);
     break;
   case CURLUPART_PASSWORD:
+    curlx_strzero(u->password);
     curlx_safefree(u->password);
     break;
   case CURLUPART_OPTIONS:
@@ -2029,6 +2033,8 @@ nomem:
       }
     }
 
+    if(what == CURLUPART_PASSWORD)
+      curlx_strzero(*storep);
     curlx_free(*storep);
     *storep = (char *)CURL_UNCONST(newp);
   }
diff --git a/src/tool_cfgable.c b/src/tool_cfgable.c
index 3feb3e7824..ab9373b240 100644
--- a/src/tool_cfgable.c
+++ b/src/tool_cfgable.c
@@ -145,7 +145,9 @@ static void free_config_fields(struct OperationConfig *config)
   curlx_safefree(config->proxy_key);
   curlx_safefree(config->key_type);
   curlx_safefree(config->proxy_key_type);
+  curlx_strzero(config->key_passwd);
   curlx_safefree(config->key_passwd);
+  curlx_strzero(config->proxy_key_passwd);
   curlx_safefree(config->proxy_key_passwd);
   curlx_safefree(config->pubkey);
   curlx_safefree(config->hostpubmd5);
@@ -158,6 +160,7 @@ static void free_config_fields(struct OperationConfig *config)
   curlx_safefree(config->request_target);
   curlx_safefree(config->customrequest);
   curlx_safefree(config->krblevel);
+  curlx_strzero(config->oauth_bearer);
   curlx_safefree(config->oauth_bearer);
   curlx_safefree(config->sasl_authzid);
   curlx_safefree(config->unix_socket_path);