diff --git a/source4/dsdb/samdb/ldb_modules/util.c b/source4/dsdb/samdb/ldb_modules/util.c
index ba1cfff..999f757 100644
--- a/source4/dsdb/samdb/ldb_modules/util.c
+++ b/source4/dsdb/samdb/ldb_modules/util.c
@@ -1049,9 +1049,20 @@ again:
 bool dsdb_module_am_system(struct ldb_module *module)
 {
 	struct ldb_context *ldb = ldb_module_get_ctx(module);
+
+	/* Debugging / mitigation for https://forge.univention.org/bugzilla/show_bug.cgi?id=49593 */
+	const void *ptr = ldb_get_opaque(ldb, DSDB_SESSION_INFO);
+        const char *pp = (const char *)ptr;
+        struct talloc_chunk *tc = discard_const_p(struct talloc_chunk, pp - TC_HDR_SIZE);
+        if (unlikely((tc->flags & (TALLOC_FLAG_FREE | ~TALLOC_FLAG_MASK)) != talloc_magic)) {
+		talloc_log("Bad talloc magic value - unknown value");
+		talloc_log("Invalid DSDB_SESSION_INFO in dsdb_module_am_system\n");
+		return false;
+	}
+
 	struct auth_session_info *session_info
 		= talloc_get_type(
-			ldb_get_opaque(ldb, DSDB_SESSION_INFO),
+			ptr,
 			struct auth_session_info);
 	return security_session_user_level(session_info, NULL) == SECURITY_SYSTEM;
 }